Annual % of total
1960 0.8830132202544275
1961 1.1597004107272288
1962 1.1569593524546893
1963 1.225982796044698
1964 1.589945487583283
1965 3.0029920455374737
1966 5.522340538437046
1967 9.680631868131869
1968 15.01324032810179
1969 15.976462399949382
1970 24.923784426187154
1971 32.51164848895021
1972 37.51713880690665
1973 39.42929248206854
1974 43.69657631302281
1975 47.02485082316854
1976 44.21152724050743
1977 45.14386481841113
1978 45.79758756369735
1979 45.029970517601576
1980 44.609250728200465
1981 49.44202383069536
1982 46.704886704886704
1983 48.279977720605785
1984 48.661425285031726
1985 50.101620978535664
1986 46.19894864536999
1987 45.40931596404364
1988 42.7366214057508
1989 47.13566257475606
1990 47.43988136164476
1991 50.95389913899139
1992 49.74592000521989
1993 49.58918367346939
1994 48.5361529665862
1995 48.07219666544968
1996 50.03962224011039
1997 49.18335115329169
1998 48.74834052240594
1999 48.99768992823558
2000 49.401697473813925
2001 49.07953106332138
2002 48.94952417910447
2003 48.34691892526106
2004 48.89191333643122
2005 48.1663517294755
2006 47.90776128519944
2007 46.377092267508964
2008 47.993156780942016
2009 50.63539055687056
2010 53.61455655526992
2011 50.519058979039464
2012 48.68924898425596
2013 48.65916687881873
2014 44.469316832343715
2015 41.46625324141421
2016 43.45396158463386