Year	Percent
1991	26.57
1992	27.26
1993	28.2
1994	29.01
1995	29.49
1996	29.95
1997	30.06
1998	28.46
1999	26.59
2000	24.91
2001	25.53
2002	25.72
2003	24.77
2004	26.38
2005	25.76
2006	25.84
2007	27.65
2008	28.23
2009	27.61
2010	24.72
2011	20.83
2012	17.55
2013	14.92
2014	18.28
2015	19.04
2016	25.49
2017	26.07
2018	26
2019	28.4