Year	Percent
1990	12.62115
1991	10.26206
1992	12.44184
1993	17.98311
1994	20.61398
1995	24.07472
1996	19.93716
1997	16.21811
1998	12.39773
1999	12.52966
2000	13.36491
2001	17.00656
2002	17.58075
2003	18.5626
2004	19.65128
2005	16.91431
2006	17.10083
2007	18.91912
2008	18.64867
2009	17.37385
2010	18.74641
2011	20.75642
2012	21.28531
2013	17.65123
2014	19.41418
2015	21.62352
2016	19.59231