Year	% of total
1971	49.494949494949495
1972	64.71631205673759
1973	70
1974	71.8266253869969
1975	72.60869565217392
1976	75.3004005340454
1977	66.08478802992519
1978	63.005780346820806
1979	61.72199170124482
1980	70.01223990208078
1981	70.03567181926277
1982	70.03329633740289
1983	69.989281886388
1984	69.98992950654582
1985	59.967453213995114
1986	65.17189835575485
1987	65.19216823785352
1988	64.73149492017417
1989	65.56776556776556
1990	63.23432343234323
1991	62.49247441300422
1992	66.64626682986537
1993	64.70937129300118
1994	60.33369214208827
1995	52.14592274678112
1996	52.060106640814354
1997	49.02325581395349
1998	53.05188199389623
1999	49.938093272802305
2000	46.049046321525886
2001	44.647887323943664
2002	41.61008729388943
2003	34.67501490757305
2004	31.92962215171618
2005	32.95870360690016
2006	30.303030303030305
2007	28.898625771758613
2008	26.57101343988376
2009	49.73039593283007
2010	82.70436058141085
2011	76.48728562980484
2012	70.14624841034338
2013	80.853753403345
2014	78.34915611814345
2015	64.53590863800108