Year	Percent
1991	35.9
1992	34.68
1993	32.36
1994	34.98
1995	35.52
1996	36.04
1997	37.75
1998	35.62
1999	32.75
2000	31.29
2001	30.11
2002	30.73
2003	28.04
2004	33.6
2005	34.13
2006	35.06
2007	37.68
2008	37.98
2009	34.91
2010	33.76
2011	31.17
2012	27.05
2013	26.23
2014	26.7
2015	29.54
2016	28.54
2017	34.46
2018	35.05
2019	32.89