And why do we have leap years in the first place?

In leap years, the number of days would be 183.

Leap years end on the next day of the week from which they begin.

March 2012 was the third month of the leap year.

December 2008 was the 12th month of the leap year.

Thus, while 1900 was not a leap year, 2000 is.

In leap years, there would be 53 weeks, or 371 days.

November 2008 was the 11th month of the leap year.

January 2012 was the first month of the leap year.

May 2012 was the fifth month of the leap year.