Year	Percent
1991	59.28
1992	50.89
1993	41.2
1994	40.07
1995	41.89
1996	41.14
1997	41.1
1998	43.34
1999	44
2000	47.45
2001	46.24
2002	43.79
2003	43.22
2004	39.39
2005	39.03
2006	40.54
2007	42.58
2008	42.55
2009	38.44
2010	38.85
2011	40.73
2012	40.05
2013	41.88
2014	43.36
2015	44.7
2016	45.42
2017	45.75
2018	45.26
2019	44.15