Autocalculate Age from Identity Card Number

My result return one extra year depending on date: If today date is 4.1.2012 then you'll get:


120103105716 result: 0
120106105717 result: -1

If Today's date is higher than IC date

Further on:

110103105716 result: 1
110106105717 result: 0

For every other year.

Edit: Rather minus than plus