Year	Percent
1986	8.1751
1987	7.7297
1988	10.0414
1989	12.9822
1990	13.537
1991	17.187
1992	16.895
1993	16.354
1994	14.783
1995	12.182
1996	11.543
1997	13.392
1998	13.886
1999	12.959
2000	12.363
2001	11.873
2002	11.665
2003	10.6329
2004	10.461
2005	10.19
2006	10.458
2007	10.167
2008	10.957
2009	17.369
2010	17.787
2011	16.352
2012	18.378
2013	16.667
2014	15.671
2015	13.6722
2016	13.389
2017	13.028