Year	Percent
1990	47.07
1991	46.58
1992	46.11
1993	45.6
1994	45.07
1995	44.52
1996	43.98
1997	44.26
1998	44.58
1999	44.97
2000	45.43
2001	46.05
2002	46.73
2003	47.48
2004	48.28
2005	49.15
2006	48.11
2007	47.14
2008	44.92
2009	45.42
2010	44.88
2011	44.53
2012	44.22
2013	43.94
2014	43.64
2015	44.88
2016	46.54
2017	47.64
2018	47.79
2019	48