Year	Percent
1985	9.73
1987	13.23
1988	13.12
1989	14.1
1990	13.13
1991	15.19
1992	15.22
1993	15.19
1994	14.83
1995	14.43
1996	12.68
1997	14.12
1998	17.45
1999	19.12
2000	22.91
2001	7.9449
2002	22.57
2003	7.7416
2004	7.9459
2005	8.1343
2006	8.8696
2007	7.7213
2008	8.6314
2009	8.8646
2010	8.6779
2011	8.2507
2012	8.1466
2013	8.0143
2014	8.3576
2016	6.7778
2017	6.6403