Years 2001, 1989, 1977, 1965, 1953, 1941, 1929, 1917 and 1903 are the years of the Snake on the Chinese Calendar during the last and present Centuries.
In Chinese culture, the Snake (the sixth animal on the Calendar) represents cunning, evil and supernatural power but with great wisdom (similar to Judeo-Christianity traditions in which the snake had tempted Adam and Eve to eat the fruit of knowledge!). In Chinese tradition, the snake is considered to be a close relative of the Dragon (notice that the Chinese Dragon actually resembles a snake but with legs!)
There are many Chinese stories about the snake, the most popular being the "legend of the white snake". In the story, two snake-demons, one White and one Red, assumed the form of two very beautiful women who came to a small town one day and met a student known as "Hui Sang". The White Snake demon fell in love with Hui Sang. They got married, raise a family, and had a new born baby. with the Red snake working as their maid.
One day, a Buddhist monk who was also an exorcist known as Fa Hoi (literally, Dharma Sea) arrived at the village temple and noticed that there was something unusual at Hui Sang's house. The exorcist monk considered the wife to be evil and waged a big battle with her. She lost and was confined under the Kim Sang Buddhist Temple. The husband died shortly after with a broken heart.
The couple left behind a orphaned son, who proved to be a very intelligent student with great wisdoms. Twenty years of hard studying enabled him to pass the civil service examination with flying colours, and he was appointed as a senior officer in the Imperial Court. When the Emperor heard of his parent's stories, he was furious. He ordered Fa Hoi to be arrested and punished. The mother White Snake was released and the father was given a great post humanus honour.
There are many variations of this legend because there is no "formal" author to the story - it simply evolved over the years. The interesting thing is that, in this legend, Buddhism had became the villian who broke up a legal marriage!!
But the story means that, if you are a snake, then, you are cunning, beautiful, attractive, with great wisdom. You are not afraid of difficulties, are determined to sucess and will finally achieve your goal.
NOTE: When and how did the twelve animals became designated as the animals of each consecutive years are not officially known. But the following folk legend is the most popular one.
ACT I - A Demand for Respect
One day the Four Celestial Generals came to see Emperor Sakra (the King of Heavens in Buddhism, some Chinese called him Jade Emperor) and reported, "Your Majesty, there is a group of animals protesting outside the Heavenly Gate demanding respect."
"What is going on?" asked Emperor Sakra. "Bring their representatives in. I like to hear what they say."
"Yes, your Majesty" replied the Celestial Generals and soon they returned with a mouse, an ox and a monkey."
"Your Majesty." said the animal representatives. "We demand respect from human beings."
"Why?"
"Because we animals provide human beings with food, milk, clothing, transportation, work and recreation. We plow their fields, pull their carts, watch their houses, sing to them and give them companionship. Therefore, we demand recognition and respect from human beings."
"OK. Your request is granted" said the King of Heavens. "The Lord Buddha is the teacher of all sentient beings in the Universe. Now he is sick and you should all visit Him. I now give the decree that the first ten animals that go to see Him on the coming New Year Day will be named the animals of the consecutive years. Now, you go to tell everyone in the Animal Kingdom."
So off they went. The mouse would inform all the household animals, the ox, all the farm animals and the monkey, all the animals in the wild, that the Lord Buddha was sick and everyone would visit Him to pay tribute, right on midnight of the coming New Year Eve.
ACT II - The Mouse Cheated the Cat
Time had come on New Year Eve. The cat came home from a big New Year Eve party and was very tired. He asked the mouse, "I am very tired. I like to sleep for a while before I go to see the Lord Buddha. Can I trust you to wake me up so that we can go together?"
"Sure" said the mouse. "Trust me. Otherwise, I would not tell you of this big occasion at all."
Then the cat went to his bed and soon was sound asleep. It was now a few moments away from midnight and the mouse thought, "If I go by myself, I will have one less competitor." So off he went without bothering waking up the cat.
ACT III - At the Temple
As everybody was waiting outside the Temple, the Celestial Generals arrived to make sure everything was in order and to act as referees. They would report back to Emperor Sakra the result of this competition. Buddha's senior student Ananda was responsible for recording the winning animals. When everybody was ready, one of the Celestial Generals shouted out the order in military fashion, "ARE YOU READY? NOW!! GO!!"
Off everybody went in the race. The ox was a very strong animal because he used to plow the land for human beings, so he was leading all the way. "How can I win the race? I am no match for the ox. I have to do some trick." thought the mouse. And he jumped onto the ox and climbed all the way to the horn. When the ox arrived, the mouse jumped down and immediately paid tribute to the Buddha. Ananda had no choice but to give the mouse a first, followed by the ox. Soon, all the other eight animals arrived in the following order: tiger, rabbit, dragon, snake, horse, goat, monkey and rooster. And Ananda wrote down all the ten animals in his report.
"STOP!!" shouted the Celestial Generals " We have ten animals already!"
But Ananda wrote in such a hurry and excitement that he put down DOG instead of STOP in his hand writing.
"We have enough animals! Would you stop writing PLEASE?!" shouted the Celestial Generals. But, in an excitement, Ananda put down PIG instead of PLEASE. Seeing this, the Celestial Generals rushed over to Ananda and took the report from him.
When daylight arrived, the Celestial Generals took the report and returned to the Heavenly Palace. "Oh Well" said Emperor Sakra, on reading the report. "Since there are twelve animals paying tribute to the Lord Buddha. I will decree that all of them will be named animals of each year from now onwards." And from then onward, each of the the twelve animals is designated for each year in the Buddhist calendar.
ACT IV - The Mouse Deserves Punishment for his Cheating
Back home the cat asked the mouse, "When are we going to see the Lord Buddha?"
"You slept like a log." replied the mouse. "Everyone went, and I am the winner!"
On hearing this, the cat was furious. "You cheater!" He jumped upon the mouse and killed him. From then onwards, all the cats in the world will try to catch and kill the mouse whenever possible.
NOTE: In Buddhism, the Four Celestial Generals stand guard at the gateway to Heaven (similar to the role of St. Peters in Catholic). Sometimes they are called the Four Great Diamond Generals.
Cross reference between Christian and Buddhist Calendar:

Mouse - 1996, 1984, 1972, 1960, 1948, 1936, 1924, 1912, 1900
Ox - 1997, 1985, 1973, 1961, 1949, 1937, 1925, 1913, 1901
Tiger - 1998, 1986, 1974, 1962, 1950, 1938, 1926, 1914, 1902
Rabbit - 1999, 1987, 1975, 1963, 1951, 1939, 1927, 1915, 1903
Dragon - 2000, 1988, 1976, 1964, 1952, 1940, 1928, 1916, 1904
Snake - 2001, 1989, 1977, 1965, 1953, 1941, 1929, 1917, 1905
Horse - 2002, 1990, 1978, 1966, 1954, 1942, 1930, 1918, 1906
Sheep - 2003, 1991, 1979, 1967, 1955, 1943, 1931, 1919, 1907
Monkey - 2004, 1992, 1980, 1968, 1956, 1944, 1932, 1920, 1908
Rooster - 2005, 1993, 1981, 1969, 1957, 1945, 1933, 1921, 1909
Dog - 2006, 1994, 1982, 1970, 1958, 1946, 1934, 1922, 1910
Pig - 2007, 1995, 1983, 1971, 1959, 1947, 1935, 1923, 1911