Year	Percent
1991	32.65
1992	31.43
1993	28.71
1994	26.33
1995	26.42
1996	26.2
1997	25.15
1998	25.88
1999	26.92
2000	28.72
2001	29.25
2002	29.47
2003	30.53
2004	29.52
2005	30.6
2006	30.36
2007	31.7
2008	31.94
2009	30.8
2010	30.32
2011	29.76
2012	28.57
2013	28.41
2014	27.83
2015	28.34
2016	28.47
2017	29.35
2018	30.46
2019	30.26