Year	Percent
1991	15.56
1992	15.86
1993	16.06
1994	15.94
1995	15.89
1996	15.78
1997	15.12
1998	15.58
1999	16.42
2000	16.02
2001	16.63
2002	15.15
2003	12.6
2004	12.81
2005	13.26
2006	14.47
2007	15.24
2008	15.66
2009	15.68
2010	15.4
2011	14.37
2012	15.42
2013	16.21
2014	15.27
2015	17.3
2016	16.2
2017	17.41
2018	17.23
2019	20.54