Year	Percent
1991	35.69
1992	34.99
1993	34.15
1994	33.47
1995	32.83
1996	32.38
1997	31.93
1998	32.35
1999	32.62
2000	32.69
2001	32.71
2002	32.63
2003	32.57
2004	32.55
2005	32.56
2006	32.54
2007	32.45
2008	32.23
2009	31.56
2010	31.19
2011	30.75
2012	30.32
2013	29.9
2014	29.56
2015	29.11
2016	28.93
2017	28.73
2018	28.48
2019	28.22