Year	% of total
1971	0
1972	0
1973	0
1974	0
1975	0
1976	25.4875283446712
1977	33.01923831959168
1978	39.787697848545164
1979	38.47234094517035
1980	71.65069430862508
1981	59.91465677179962
1982	54.50595527467185
1983	57.510656436487636
1984	56.52499438468641
1985	57.59969307846809
1986	55.38345296562146
1987	50.877318116975744
1988	49.3309950636529
1989	51.27968073468004
1990	50.98688012946481
1991	50.30333328829498
1992	46.96191750821268
1993	46.63115114235501
1994	47.6001362832989
1995	45.309976902479406
1996	44.147200189884686
1997	44.423781451657895
1998	42.48362021583801
1999	41.90984329706339
2000	46.03180892456673
2001	52.4698331001773
2002	55.84466896201389
2003	54.843790849673205
2004	56.94136043784206
2005	56.49258476982126
2006	53.256280520740326
2007	50.240638202954834
2008	48.825661116552396
2009	44.81255930938539
2010	46.1408690074021
2011	43.33745206476405
2012	44.68345111896348
2013	52.751771900977765
2014	51.160016163896785
2015	55.80369809893124