Year	Percent
1983	23.80517
1984	19.86469
1985	25.82342
1986	28.58604
1987	33.113
1988	26.7148
1989	33.01921
1990	33.22727
1991	26.07026
1992	21.07819
1993	21.24022
1994	23.20652
1995	22.63662
1996	19.7145
1997	18.83642
1998	17.14602
1999	18.99283
2000	19.914
2001	18.35379
2002	19.54369
2003	16.84624
2004	23.23849
2005	24.11931
2006	28.37718
2007	32.26644
2008	40.5587
2009	39.89312
2010	34.65956
2011	27.49707
2012	23.04495
2013	25.91982
2014	26.43062