Year	Percent
1995	28.44564
1996	27.28727
1997	25.43568
1998	21.0576
1999	20.5076
2000	19.14767
2001	21.96939
2002	20.38476
2003	20.67294
2004	20.71768
2005	19.16766
2006	18.77775
2007	19.44255
2008	19.12187
2009	17.16287
2010	17.08042
2011	17.6254
2012	17.81454
2013	18.11755
2014	18.65909
2015	18.83553
2016	18.51496
2017	17.87642