Year	Percent
1986	14.6069
1987	12.6074
1988	11.6051
1989	10.2599
1990	9.46
1991	9.5239
1992	11.1264
1993	15.3047
1994	16.4962
1995	15.2284
1996	15.1654
1997	13.8661
1998	11.6075
1999	9.0048
2000	7.8913
2001	6.1602
2002	6.7489
2003	6.9913
2004	7.0341
2005	5.9602
2006	5.3772
2007	5.4545
2008	8.8958
2009	16.1465
2010	17.9235
2011	19.3593
2012	23.0082
2013	23.8101
2014	21.6954
2015	18.9394
2016	16.3364
2017	13.8931