Year	Percent
1990	1.669
1991	3.996
1992	8.196
1993	13.071
1994	11.826
1995	16.348
1996	16.603
1997	15.4369
1998	11.7586
1999	21.829
2000	19.6677
2001	31.8083
2002	24.7267
2003	31.9285
2004	23.9058
2005	13.8222
2006	15.1217
2007	7.1537
2008	11.2913
2009	21.8329
2010	29.503
2011	20.5856
2012	18.4665
2013	19.7017
2014	10.0207
2015	12.1872
2016	10.5804
2017	9.9734