Year	Percent
1990	12.66
1991	14.08
1992	12.54
1993	13.24
1994	14.06
1995	14.39
1996	15.3
1997	16.03
1998	17.77
1999	17.34
2000	18.08
2001	18.92
2002	19.19
2003	18.79
2004	17.99
2005	17.96
2006	17.92
2007	18.17
2008	17.61
2009	17.02
2010	16.61
2011	14.62
2012	14.72
2013	13.45
2014	11.99
2015	11.62
2016	11.08
2017	11.3
2018	11.52
2019	11.76