Year	Percent
1971	40.86699
1972	19.69537
1973	19.23776
1974	24.26852
1975	6.53086
1976	7.17011
1977	4.03119
1978	3.64093
1979	6.48734
1980	8.02113
1981	3.66511
1982	2.88258
1983	5.88535
1984	2.179
1985	4.50024
1986	1.7099
1987	1.70607
1988	3.90952
1989	1.71295
1990	0.56495
1991	0.79247
1992	0.4039
1993	0.18272
1994	0.14683
1995	0.14034
1996	0.12491
1997	0.08888
1998	0.08757
1999	0.12189
2000	2.08516
2001	3.48878
2002	6.22143
2003	5.7164
2004	7.7602
2005	12.52902
2006	50.76018
2007	94.93248
2008	109.66935
2009	113.43268
2010	114.16305
2011	103.35448
2012	90.40716
2013	70.63513
2014	61.37264
2015	53.4829
2016	30.55938