Year	Percent
1990	27.98715
1991	27.08194
1992	26.6131
1993	26.30602
1994	26.30642
1995	26.29546
1996	25.86849
1997	25.46947
1998	25.26257
1999	24.67284
2000	24.31924
2001	24.17883
2002	24.03933
2003	23.49066
2004	23.45272
2005	23.29568
2006	23.43024
2007	23.79145
2008	23.58508
2009	21.93331
2010	21.9248
2011	21.73867
2012	21.42657
2013	21.32794
2014	21.01755
2015	21.17655
2016	21.43804
2017	21.36166