Year	Percent
1993	28.44933
1994	28.16805
1995	27.46163
1996	25.48514
1997	24.31178
1998	22.96931
1999	22.95249
2000	22.56354
2001	22.3173
2002	21.32291
2003	21.49253
2004	22.25834
2005	21.90065
2006	21.22011
2007	21.3154
2008	19.68812
2009	18.09088
2010	17.97758
2011	18.23516
2012	17.96117
2013	18.01774
2014	18.29028
2015	19.16248
2016	19.02944
2017	19.45182