Year	Percent
1991	32.29
1992	31.49
1993	30.43
1994	31.66
1995	28.18
1996	29.96
1997	30.7
1998	36.87
1999	35.17
2000	33.51
2001	32.83
2002	31.35
2003	31.33
2004	30.86
2005	30.87
2006	32.71
2007	32.41
2008	32.82
2009	31.22
2010	29.86
2011	29.46
2012	28.82
2013	29.04
2014	27.5
2015	28.37
2016	27.68
2017	28.77
2018	25.21
2019	23.82