Year	Percent
1989	30.59337
1990	32.61208
1991	36.70933
1992	48.72571
1993	42.84645
1994	44.83261
1995	52.22961
1996	49.41727
1997	50.59552
1998	51.82537
1999	49.89011
2000	49.71802
2001	51.46585
2002	53.89964
2003	53.81746
2004	50.65827
2005	48.80604
2006	49.72148
2007	50.67307
2008	50.69575
2009	53.76655
2010	53.12026
2011	53.7557
2012	54.09417
2013	55.96646
2014	55.56256
2015	55.94434
2016	56.6205
2017	56.18408