Year	Percent
1991	57.28
1992	56.37
1993	53.61
1994	50.32
1995	49.21
1996	48.04
1997	45.87
1998	47.28
1999	40.49
2000	38.66
2001	40.08
2002	41.35
2003	42.94
2004	44.05
2005	44.19
2006	43.88
2007	43.05
2008	42.44
2009	42.14
2010	43.21
2011	38.46
2012	39.52
2013	40.2
2014	43.95
2015	44.73
2016	46.43
2017	46.47
2018	46.61
2019	46.52