Year	Percent
1991	50.18
1992	50.93
1993	51.7
1994	50.13
1995	47.82
1996	48.17
1997	49.49
1998	50.5
1999	50.7
2000	49.45
2001	48.04
2002	45.09
2003	44.4
2004	43.73
2005	45.56
2006	46.04
2007	45.96
2008	45.04
2009	42.83
2010	43.06
2011	42.67
2012	43.19
2013	42.51
2014	41.62
2015	41.6
2016	41.64
2017	41.62
2018	41.52
2019	42.42