Year	Percent
1990	10.99
1991	11.08
1992	11.19
1993	11.32
1994	11.45
1995	11.55
1996	11.66
1997	11.76
1998	11.86
1999	11.97
2000	12.09
2001	12.12
2002	12.14
2003	12.15
2004	12.57
2005	11.77
2006	11
2007	10.2
2008	9.45
2009	9.25
2010	8.73
2011	8.13
2012	7.57
2013	7.06
2014	6.64
2015	6.31
2016	5.95
2017	5.56
2018	5.22
2019	4.92