Year	Percent
1990	10.55
1991	10.7
1992	10.59
1993	10.47
1994	10.36
1995	10.25
1996	10.16
1997	10.07
1998	9.98
1999	9.89
2000	9.77
2001	9.66
2002	9.55
2003	10.22
2004	10.93
2005	10.31
2006	13.38
2007	15.59
2008	16.69
2009	17.21
2010	16.3
2011	16.75
2012	15.87
2013	15.25
2014	16.16
2015	15.82
2016	15.39
2017	14.63
2018	14.73
2019	14.71