Year	Percent
1987	40
1988	37.03704
1989	35.71429
1990	30
1991	30.50847
1992	12.1875
1993	59.78044
1994	44.83945
1995	59.09509
1996	65.19989
1997	45.03277
1998	40.57163
1999	43.64779
2000	41.06069
2001	41.97199
2002	40.29841
2003	38.88562
2004	37.87185
2005	37.06192
2006	35.78695
2007	37.70963
2008	60.54579
2009	60.91024
2010	59.13116
2011	65.86929
2012	66.57986
2013	63.42771
2014	60.6696
2015	56.96627