Year	Percent
1990	23.83313
1991	22.33382
1992	16.90339
1993	15.21378
1994	21.23896
1995	17.81544
1996	16.64215
1997	14.94287
1998	16.57578
1999	17.05033
2000	17.15913
2001	17.2719
2002	15.41408
2003	19.92464
2004	21.21666
2005	20.46719
2006	21.11193
2007	22.88227
2008	22.1789
2009	19.03347
2010	18.4509
2011	17.73923
2012	18.97682
2013	19.82041
2014	19.55373
2015	20.20226
2016	20.04105