Year	Percent
1990	56.82
1991	56.44
1992	55.44
1993	51.56
1994	54.04
1995	53.47
1996	52.99
1997	51.69
1998	51.84
1999	51.72
2000	48.8
2001	48.6
2002	48.27
2003	46.94
2004	45.96
2005	46.03
2006	45.06
2007	45.08
2008	45.79
2009	46.64
2010	47.7
2011	48.78
2012	48.73
2013	49.63
2014	50.11
2015	50.97
2016	51.72
2017	52.54
2018	52.92
2019	52.75
2020	50.38