Year	Percent
1990	1.77
1991	5.405
1992	12.15
1993	16.19
1994	20.37
1995	16.2745
1996	16.4702
1997	12.0287
1998	13.303
1999	10.7151
2000	9.9762
2001	9.3169
2002	8.6461
2003	8.678
2004	8.8939
2005	7.1822
2006	6.8729
2007	6.8091
2008	5.7738
2009	7.0071
2010	7.3991
2011	7.5325
2012	8.1179
2013	8.1315
2014	8.3004
2015	9.1583
2016	8.1992
2017	8.6761