Year	Percent
1991	43.22
1992	43.79
1993	48.03
1994	51.85
1995	52.6
1996	52.13
1997	50.3
1998	47.39
1999	47.74
2000	48.58
2001	47.12
2002	42.88
2003	42.1
2004	43.79
2005	46.38
2006	46.24
2007	46.96
2008	47.81
2009	45.57
2010	45.55
2011	44.74
2012	43.65
2013	44.52
2014	44.5
2015	44.62
2016	44.74
2017	45.36
2018	44.57
2019	43.72