Year	Percent
1991	54.91
1992	54.74
1993	54.91
1994	54.67
1995	54.5
1996	51.74
1997	51.18
1998	49.39
1999	48.86
2000	48.78
2001	48.72
2002	49.38
2003	48.6
2004	50.45
2005	50.71
2006	50.59
2007	51
2008	51.37
2009	49.7
2010	49.02
2011	48.34
2012	48
2013	47.11
2014	46.38
2015	44.06
2016	40.2
2017	39.63
2018	40.02
2019	41.03