Year	Percent
1991	33.56381
1992	32.64021
1993	30.67679
1994	30.27941
1995	29.82047
1996	28.88933
1997	28.60525
1998	28.44056
1999	27.78224
2000	27.8803
2001	27.21444
2002	26.56021
2003	26.41743
2004	26.65598
2005	26.60236
2006	27.25077
2007	27.47178
2008	27.0463
2009	24.94765
2010	27.14208
2011	27.45668
2012	27.5925
2013	27.08669
2014	27.40233
2015	27.48611
2016	27.46594
2017	27.59946