There were no leap years on St. Valentine's Day in 1998. A year cannot be in a day. 1998 itself was not a leap year.
zero
From 1898 until 1998 there were 24 leap years: every four years from 1904 through 1996 inclusive.
leap years 1998-2011
There were 20 leap years from 1929 through 2008. (the next one is 2012):19321936194019441948195219561960196419681972197619801984198819921996200020042008
There were 5 years between 1977 and 1998. They were 1980, 1984, 1988, 1992, and 1996.
16 leap years
24 leap years
Leap years occur every 4 years.
without leap years 60153 With leap years 60174
7 leap years!
1 if it is a leap year
1998 was not a leap year, so February had 28 days in 1998.