Year	Percent
1986	16.3334
1987	14.0101
1988	10.2319
1989	8.2466
1990	7.9044
1991	6.1982
1992	8.7328
1993	9.921
1994	12.539
1995	15.0801
1996	14.5523
1997	11.0483
1998	8.4504
1999	7.6794
2000	5.4789
2001	6.5496
2002	9.1798
2003	10.787
2004	12.5914
2005	13.8666
2006	14.9098
2007	13.8065
2008	13.6
2009	19.0774
2010	21.645
2011	29.0162
2012	36.7485
2013	36.7489
2014	34.1804
2015	29.5831
2016	27.2327
2017	22.4028