Year	Percent
1990	9.92
1991	11.03
1992	13.15
1993	15.95
1994	20.8
1995	22.58
1996	21.27
1997	19.41
1998	19.33
1999	18.9
2000	18.06
2001	17.29
2002	17.56
2003	14.34
2004	11.64
2005	12.25
2006	12.85
2007	12.97
2008	13.1
2009	13.23
2010	11.68
2011	10.76
2012	9.9
2013	9.1
2014	9.49
2015	10.63
2016	11.21
2017	10.91
2018	11.5
2019	11.22