Year	Percent
1979	6.04878
1980	6.5893
1981	6.46757
1982	6.72188
1983	8.84584
1984	7.88789
1985	9.44648
1986	10.21323
1987	13.34539
1988	13.18334
1989	12.91304
1990	14.08694
1991	12.71986
1992	10.90329
1993	10.04504
1994	12.69835
1995	12.23735
1996	10.59107
1997	9.06914
1998	8.17388
1999	8.32273
2000	11.22299
2001	9.04749
2002	8.95114
2003	8.1928
2004	7.59748
2005	7.84741
2006	8.09454
2007	7.79772
2008	8.85127
2009	10.87547
2010	12.31594
2011	9.71738
2012	7.53297
2013	7.86512
2014	8.12676
2015	11.38576