At the time I write this, you are not even one full day old yet.
This answer will be wrong tomorrow, and it'll change every day.
As of today (31 July 2012) you are 8 years old.
If you turned 21 on December 31, 2009, then you were born on December 31, 1988.
Sir Alex Ferguson is 76 years old. He was born December 31, 1941.
You would turn 24 years old on December 31, 2013.
31 (2010)
She was born on December 31 1969
As of September 2011, someone born on December 1, 1979 would be 31 years old.
On your birthday in 2012, whenever that is, you turn 31 .
In April 2012, you turned 31.
31 years old, or 2012 minus 1981 equals 31.
She was born 30th December 1980 - making her currently 31 years old (on 7th Feb 2012)
Donna Summer was born on December 31, 1948.