Year	Percent
1974	8.29173
1975	9.14651
1976	9.30597
1977	8.71333
1978	9.42804
1979	9.82004
1980	9.1481
1981	9.33826
1982	9.39444
1983	9.39381
1984	9.43236
1985	10.21164
1986	10.56828
1987	10.54903
1988	10.49676
1989	10.60987
1990	10.1287
1991	10.30843
1992	9.93779
1993	8.65063
1994	9.1032
1995	9.35157
1996	9.35628
1997	9.13103
1998	8.22283
1999	8.75509
2000	8.92925
2001	8.18869
2002	8.79358
2003	9.23122
2004	9.70021
2005	10.22401
2006	11.37051
2007	12.26585
2008	11.08762
2009	9.9427
2010	10.50717
2011	10.17739
2012	10.83677
2013	11.00163