Year	Percent
1990	14.55
1991	14.55
1992	14.86
1993	15.19
1994	15.54
1995	15.91
1996	16.32
1997	16.75
1998	17.21
1999	17.7
2000	18.23
2001	18.82
2002	18.72
2003	18.6
2004	17.98
2005	18.19
2006	18.89
2007	17.5
2008	17.62
2009	16.87
2010	15.43
2011	14.1
2012	14.63
2013	14.38
2014	13.98
2015	14.16
2016	13.83
2017	14.5
2018	15.09
2019	15.68