Year	Percent
1990	43.59
1991	43.98
1992	43.96
1993	44.28
1994	44.71
1995	45.19
1996	45.07
1997	45.35
1998	45.51
1999	45.88
2000	46.21
2001	46.59
2002	46.97
2003	47.3
2004	47.38
2005	47.56
2006	47.63
2007	47.67
2008	47.26
2009	46.83
2010	46.54
2011	46.69
2012	46.78
2013	46.76
2014	46.74
2015	46.79
2016	46.85
2017	46.91
2018	47.1
2019	47.5
2020	45.32