Year	% of total
1971	3.907380607814761
1972	4.980340760157274
1973	6.577344701583435
1974	6.028368794326241
1975	11.042944785276074
1976	8.882783882783883
1977	8.312342569269521
1978	8.527755430410297
1979	11.791044776119403
1980	13.180901143241424
1981	14.551971326164875
1982	15.270618556701033
1983	17.07462686567164
1984	25.132275132275133
1985	31.05238319962246
1986	35.5902004454343
1987	34.87068965517241
1988	42.857142857142854
1989	40.97834803528468
1990	39.30589184826473
1991	39.07358983937243
1992	38.88518024032043
1993	41.41802067946824
1994	50.445186421814135
1995	54.57459926017263
1996	53.865652724968314
1997	56.33295838020247
1998	70.59676250302005
1999	62.0392325932313
2000	49.53106682297773
2001	49.797398165920235
2002	45.126282557221785
2003	49.49308755760369
2004	49.260117668033516
2005	39.827127659574465
2006	32.85204412719014
2007	29.551492420690735
2008	28.64693446088795
2009	17.303273980470994
2010	22.988200981042027
2011	16.092419943250913
2012	19.977636973537084
2013	22.813750306197438
2014	35.15575333757152
2015	39.01690670006261