Year	Percent
1991	44.66
1992	46.24
1993	47.73
1994	47.39
1995	47.56
1996	47.16
1997	46.75
1998	46.96
1999	47.14
2000	46.55
2001	45.93
2002	45.26
2003	46.12
2004	45.52
2005	45.75
2006	43.73
2007	44.22
2008	46.37
2009	43.87
2010	41.43
2011	39.93
2012	42.77
2013	43.55
2014	41.01
2015	39.67
2016	39.94
2017	38.61
2018	40.12
2019	38.98