Year	Percent
1991	51.81
1992	50.72
1993	46.94
1994	49.4
1995	49.39
1996	49.48
1997	48.16
1998	48.27
1999	47.74
2000	45.63
2001	44.53
2002	43.27
2003	42
2004	40.98
2005	41.13
2006	41.13
2007	41.08
2008	41.34
2009	40.78
2010	42.61
2011	44.49
2012	44.75
2013	45.3
2014	45.16
2015	45.75
2016	46.12
2017	46.85
2018	47.16
2019	45.54
2020	43.37