Year	Percent
1991	49.16
1992	46.82
1993	45.34
1994	44.64
1995	44.36
1996	43
1997	43.78
1998	42.82
1999	39.9
2000	39.73
2001	39.32
2002	34.56
2003	35.47
2004	34.88
2005	34.56
2006	35.82
2007	36.25
2008	35.8
2009	32.18
2010	35.76
2011	33.93
2012	35.23
2013	34.4
2014	36.45
2015	37.94
2016	36.94
2017	36.49
2018	36.98
2019	37.56