Beijing hosted the 2008 Olympic Games.

In 2007,

2007-3=2004 (leap year)

So 1796 to 2004***208

With arithmetic progression's formula:

(2004- 1796)/4+ 1=53

Because every four years is a leap, every hundred years is not a leap, and every four hundred years is a leap.

So 1800 and 1900 are not leap years.

53-2=5 1

A: There are 5 1 leap years.

Note: In 2008, there will be 52 leap years.