Year	Percent
1986	6.417
1987	6.1136
1988	6.8537
1989	6.3684
1990	7.2755
1991	6.9065
1992	8.5205
1993	8.2495
1994	9.5485
1995	11.0159
1996	12.4633
1997	13.2299
1998	12.1713
1999	11.224
2000	11.2419
2001	8.0766
2002	9.9583
2003	9.2275
2004	10.1417
2005	7.5254
2006	7.3193
2007	7.7203
2008	8.9806
2009	13.2602
2010	13.8897
2011	14.6905
2012	17.9166
2013	19.6971
2014	19.4004
2015	18.7109
2016	17.2443
2017	15.9203