Year	Percent
1991	45.22
1992	42.16
1993	44.24
1994	41.45
1995	42.52
1996	41.98
1997	38.89
1998	38.37
1999	38.88
2000	39.2
2001	40.59
2002	38.36
2003	38.78
2004	39.73
2005	38.02
2006	38.61
2007	37.62
2008	38.27
2009	36.3
2010	35.12
2011	31.04
2012	28.91
2013	24.82
2014	27.66
2015	27.74
2016	27.8
2017	28.38
2018	32.11
2019	33.26