Year	Percent
1990	19.48288
1991	17.49383
1992	18.71093
1993	15.04017
1994	17.23652
1995	15.6895
1996	16.10562
1997	16.0501
1998	16.18819
1999	16.95431
2001	16.5407
2002	15.44001
2003	14.85952
2004	15.31706
2005	14.79477
2006	13.71153
2007	13.8671
2008	14.21847
2009	12.49873
2010	13.24762
2011	17.12016
2012	16.15065
2013	15.66963
2014	16.96958
2015	16.83081
2016	14.93719