Annual % of total
1960 44.199071887423855
1961 44.15911346707507
1962 49.0496657421752
1963 51.626279505991334
1964 53.97489236859649
1965 56.08172970749894
1966 59.44922183786405
1967 60.624610711811265
1968 62.18319546684407
1969 64.16108790981964
1970 65.65402953079007
1971 53.76837540189243
1972 54.737855216445205
1973 55.90322435580634
1974 56.40333649977598
1975 57.89461333778218
1976 58.77763546324363
1977 60.38238009435755
1978 61.75136836527048
1979 62.21283799077831
1980 62.314071758019296
1981 62.29297557425206
1982 63.00320912005328
1983 63.10778131394087
1984 63.79539223692625
1985 64.26111809599348
1986 64.76280593261943
1987 65.5113570315994
1988 66.15443088902884
1989 66.46162796618188
1990 76.69718383307315
1991 76.36382154881387
1992 75.71218028987339
1993 75.63789335893793
1994 75.09485146545171
1995 75.57995814702065
1996 75.57529887559434
1997 75.5841914725533
1998 75.3867920519548
1999 75.53247985303578
2000 75.65244610182147
2001 75.8757957454327
2002 76.16687817287864
2003 77.0799977553992
2004 77.92257262729414
2005 78.54523021402849
2006 79.08526560878872
2007 79.51469341059747
2008 79.74982176944336
2009 79.77640243349181
2010 80.34054451336578
2011 80.74991333784904
2012 80.68673705792867
2013 80.48204504128388
2014 80.76271553996799
2015 88.9604814478969