Year	Percent
1990	14.6
1991	14.99
1992	15.38
1993	15.82
1994	16.16
1995	16.05
1996	16.36
1997	16.78
1998	16.97
1999	16.75
2000	16.65
2001	16.36
2002	15.71
2003	16.02
2004	16.36
2005	17.76
2006	17.66
2007	16.25
2008	14.93
2009	15.46
2010	15.1
2011	15.2
2012	14.11
2013	14.18
2014	15.31
2015	15.53
2016	15.78
2017	16.04
2018	16.27
2019	17.33