Year	% of total
1971	13.406113537117903
1972	25.478194338179033
1973	27.51304347826087
1974	28.78096479791395
1975	34.10828999694096
1976	31.99334627113945
1977	29.006490264603098
1978	27.734731084776666
1979	18.797927461139896
1980	19.477796836287403
1981	20.879888268156424
1982	18.22620016273393
1983	20.400837571043972
1984	18.19101285941338
1985	15.575221238938052
1986	27.07367336424523
1987	34.34570678665167
1988	29.185218165627784
1989	21.91932624113475
1990	22.97465724968841
1991	19.728408473655623
1992	17.162259491717254
1993	25.580221997981837
1994	25.614646904969483
1995	49.354945418458485
1996	47.368001276120594
1997	47.105127639226076
1998	57.61875385564467
1999	53.57115160915084
2000	68.28111638031564
2001	77.35610793566397
2002	75.5956678700361
2003	70.88309808179515
2004	70.70883931092912
2005	65.99792638672888
2006	64.95167136528394
2007	62.607428255515906
2008	56.72178988326848
2009	51.373847245211635
2010	45.90233186887462
2011	46.704790850195955
2012	43.37296506310591
2013	43.392006925407586
2014	55.02678633549015
2015	55.52563270603505