Year	Percent
1991	49.57
1992	49.1
1993	48.93
1994	48.8
1995	48.96
1996	48.05
1997	47.18
1998	46.36
1999	46.41
2000	45.48
2001	44.16
2002	44.16
2003	44
2004	43.23
2005	42.49
2006	41.88
2007	40.95
2008	39.76
2009	39.48
2010	39.41
2011	39.51
2012	39.62
2013	39.77
2014	39.98
2015	40.19
2016	40.31
2017	40.5
2018	40.65
2019	40.77
2020	38.79