DATENAME Function

hi, how doin ??
in fact i found a problem with DATENAME function. i execute this select to return the week number, i change only the year part, like that :

SELECT DATENAME(wk,'03/01/1993') --> Result = 2
SELECT DATENAME(wk,'03/01/1994') --> Result = 2
SELECT DATENAME(wk,'03/01/1995') --> Result = 1
SELECT DATENAME(wk,'03/01/1996') --> Result = 1
SELECT DATENAME(wk,'03/01/2000') --> Result = 2
SELECT DATENAME(wk,'03/01/2001') --> Result = 1
...... etc
the result must be '1', but i don't know why it returns '2'

can someone help me plz ??????? thank u