Year	Percent
1991	40.63
1992	40.77
1993	41.73
1994	43.36
1995	45.62
1996	44.46
1997	44.72
1998	44.78
1999	43.39
2000	44
2001	44.51
2002	44.96
2003	45.46
2004	46.01
2005	46.22
2006	46.5
2007	46.76
2008	46.98
2009	47.01
2010	47.94
2011	47.85
2012	47.64
2013	48.49
2014	48.34
2015	48.18
2016	48.11
2017	48.13
2018	48.14
2019	48.08
2020	44.13