• 1972 to 1974 4
• 1975 to 1979 10
• 1980 to 1984 23
• 1985 to 1989 22
• 1990 to 1994 14
• 1995 to 1999 29
• 2000 to 2004 56
• 2005 to 2009 53
• 2010 to 2014 48
• 2015 to 2017 2