Year	Percent
1990	28.86115
1991	27.73153
1992	26.94874
1993	26.90474
1994	26.86058
1995	26.51026
1996	26.05445
1997	25.2925
1998	25.43611
1999	24.71083
2000	24.64958
2001	23.69439
2002	23.64144
2003	24.0731
2004	23.91949
2005	24.58376
2006	25.59829
2007	25.59133
2008	25.53131
2009	26.92748
2010	25.06376
2011	26.34295
2012	26.18874
2013	25.03732
2014	25.41767
2015	23.54904
2016	22.25826
2017	23.04841