Year	Percent
1992	12.955
1993	13.961
1994	17.505
1995	19.988
1996	20.52
1997	24.052
1998	27.565
1999	25.78
2000	22.197
2001	19.199
2002	16.906
2003	18.796
2004	18.651
2005	16.838
2006	17.14
2007	14.415
2008	15.089
2009	18.864
2010	17.4468
2011	15.7333
2012	15.2693
2013	14.6986
2014	14.2661
2015	17.0161
2016	17.2829
2017	17.0477