Year	Percent
1991	47.85
1992	48.22
1993	48.59
1994	48.21
1995	47
1996	43.25
1997	44.87
1998	47.35
1999	44.82
2000	45.05
2001	44.85
2002	42.95
2003	43.21
2004	41.52
2005	41.99
2006	42.8
2007	45.82
2008	43.52
2009	38.45
2010	37.17
2011	33.8
2012	37.87
2013	37.1
2014	35.67
2015	35.41
2016	32.92
2017	34.36
2018	33.75
2019	31.61