Year	% of total
1971	7.046180361940488
1972	8.089504822855039
1973	9.555569806964662
1974	10.81896376014023
1975	3.5870516185476813
1976	14.88861428620465
1977	18.971566039627117
1978	22.5756750447436
1979	22.12896370104569
1980	9.634590878108051
1981	18.573383900310816
1982	16.343112503990017
1983	17.284372331340734
1984	16.039460281580087
1985	9.408504831657801
1986	13.516521370465567
1987	12.585552870661608
1988	8.893815883805528
1989	10.921411715072972
1990	18.38467399586372
1991	10.798725419432072
1992	8.20370882922779
1993	9.795226764727088
1994	10.494051073708647
1995	9.784699490432963
1996	10.925835370823146
1997	12.00916917477427
1998	7.738896366083446
1999	7.6020508775389475
2000	6.544845380675472
2001	10.034158838599486
2002	6.536950762766054
2003	6.588683351468988
2004	3.8921042850315932
2005	3.1878545099557334
2006	2.5615260698279028
2007	1.7771147828060903
2008	1.0776525648131041
2009	1.7855596543184218
2010	1.1415562777347037
2011	1.2403425861707447
2012	1.2777758872971041
2013	0.956676233429001
2014	0.7453759087144566
2015	0.7190315827796487