Can anyone help me create this function?

I need to be able to input two dates and get the number of years (as an integer) between the dates.
For example:
1/4/2003 - 5/14/2008 would return 6 because we are currently in the sixth year.

6/11/2003 - 5/14/2008 would return 5 because we are in the fifth year.

I would also need to be sure that 5/14/2003 - 5/14/2008 would return 5.

Any help is greatly appreciated!