Social Security Tax

请教一个问题。我看到“foreign students in F-1, J-1, M-1, Q-1 or Q-2 nonimmigrant status who have been in the United States less than 5 calendar years are still NONRESIDENT ALIENS and are still exempt from social security/Medicare taxes. ” 但是不太清楚这个5 calendar years是怎么算的？比如我是08年8月到美国的，到现在为止是已经有5个calendar year了呢还是还不到？

不到

08算一年,然后往后算