Year	Percent
1990	28.61201
1991	27
1992	27.40543
1993	40.63249
1994	44.41185
1995	41.15047
1996	39.36426
1997	37.91048
1998	39.58252
1999	40.03574
2000	39.89468
2001	44.34759
2002	44.07058
2003	43.2528
2004	41.81646
2005	39.62832
2006	40.83288
2007	40.47155
2008	37.99144
2009	40.48291
2010	43.474
2011	44.12824
2012	43.29273
2013	45.42179
2014	45.65221
2015	47.7417
2016	48.523
2017	46.94265