Year	Percent
1972	37.43169
1973	37.21713
1974	32.67768
1977	4.6158
1978	7.59796
1979	2.17843
1980	2.69991
1981	3.73615
1982	3.44478
1983	3.2383
1984	3.12861
1985	1.938
1986	2.09502
1987	1.26738
1988	1.22982
1989	1.17599
1990	1.54507
1991	0.25561
1992	0.08581
1993	1.09262
1994	1.42276
1995	1.14617
1996	0.96508
1997	1.17308
1998	1.49233
2001	1.03729
2002	1.18205
2003	1.32474
2004	1.32443
2005	1.02997
2006	0.97048
2007	1.08652
2008	0.87582
2009	0.97119
2010	0.97947
2011	0.79978
2012	0.71631
2013	0.77745
2014	0.89014
2015	1.38078