Annual % of total
1960 90.68476249228871
1961 90.18441403926234
1962 91.45216124332201
1963 90.88066701406983
1964 90.68883610451306
1965 90.35555555555555
1966 90.7724425887265
1967 86.56367041198502
1968 85.36478811708169
1969 85.04954760878933
1970 25.86475942782835
1971 27.597548213484828
1972 22.13740458015267
1973 29.31034482758621
1974 46.06072252113759
1975 55.9125315391085
1976 81.8804319199368
1977 82.33317330772924
1978 78.69203329369797
1979 77.54504504504504
1980 75.77937649880097
1981 74.90690939180803
1982 73.66846199880311
1983 71.96279422930904
1984 66.56916005014625
1985 70.16632016632018
1986 61.07670319199619
1987 61.90341711380967
1988 60.21828535273648
1989 48.79581151832461
1990 60.1141010320478
1991 65.56940469688695
1992 56.91351113412739
1993 36.71536494845361
1994 40.82364859813084
1995 41.423070580474935
1996 43.19483465027802
1997 53.67121325361236
1998 48.36484510809004
1999 44.38230905468231
2000 41.210928244881735
2001 44.657135193133044
2002 41.51101538925769
2003 45.4185481124042
2004 41.22878522377457
2005 42.90517492394611
2006 44.67337301587302
2007 34.630844562535586
2008 37.13453239245027
2009 34.562560734892195
2010 31.786883029978586
2011 39.994464501409205
2012 35.5196272153188
2013 36.66045238560177
2014 41.869412672045556
2015 39.798869502868065
2016 36.26541296288025