24
Including 1988 itself, there were 7 of them. They were 1988, 1992, 1996, 2000, 2004, 2008 and 2012.
There are 23 years between 1988 and 2011.
There were 8 of them. They were 1984, 1988, 1992, 1996, 2000, 2004, 2008 and 2012.
There are 62 years between 1950 and 2012.
There are 27 years between 1985 and 2012.
4006
Including 1980, there are 9 leap years between 1980 and 2014. They are 1980, 1984, 1988, 1992, 1996, 2000, 2004, 2008 and 2012.
2012 -1990 =22
There are 31 years between 1981 and 2012.
4006
There are 48 years between 1964 to 2012. This is because 2012-1964=48.