Year	Percent
1990	4.775
1991	8.499
1992	16.19
1993	26.056
1994	25.182
1995	20.8679
1996	22.4348
1997	22.6597
1998	18.0822
1999	17.0639
2000	10.801
2001	12.7038
2002	13.412
2003	15.4717
2004	19.8091
2005	22.0051
2006	20.9668
2007	18.7725
2008	19.7219
2009	26.26
2010	25.8548
2011	23.2901
2012	25.0163
2013	24.7551
2014	24.2306
2015	21.2202
2016	20.5061
2017	18.797