Year	Percent
1990	46.33274
1991	60.12047
1992	61.256
1993	60.75417
1994	73.10079
1995	62.18693
1996	55.98956
1997	58.27447
1998	52.83943
1999	49.80216
2000	50.54329
2001	46.14881
2002	46.58687
2003	50.035
2004	45.30238
2005	43.22971
2006	39.25021
2007	39.15081
2008	40.65576
2009	43.0044
2010	45.31719
2011	47.35401
2012	48.40002
2013	48.19707
2014	47.04655
2015	41.86527
2016	42.76988
2017	50.39951