Year	Percent
1973	5.01748
1982	22.22097
1983	17.97706
1984	22.06483
1985	23.50404
1986	35.0667
1987	25.75962
1988	19.32939
1989	19.84414
1990	21.32064
1991	21.74145
1992	20.44857
1993	20.07662
1994	19.72644
1995	19.97233
1999	11.14675
2000	12.6978
2001	14.53424
2002	17.30717
2004	23.39299
2005	33.38995
2006	33.10222
2007	37.54822
2008	49.3657
2009	47.70604
2010	52.22149
2011	48.87671
2012	46.96135
2013	45.12908
2014	45.07891
2015	45.48064