Year	% 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