Year	Percent
1973	42.51163
1976	49.14515
1977	52.28954
1978	54.58415
1979	46.50644
1980	48.05273
1981	64.30249
1982	51.00543
1983	53.23116
1984	57.32235
1985	58.93165
1986	62.41096
1987	63.71077
1988	64.57234
1989	69.14187
1990	74.98967
1991	69.42836
1993	70.11993
1994	77.08764
1995	86.93454
1996	85.21987
1997	87.50851
1999	86.85097
2000	85.80789
2001	87.58049
2002	92.96535
2003	96.9692
2004	100.84742
2005	103.8829
2007	101.77974
2008	91.90363
2009	89.95018
2010	98.84318
2013	97.23763
2014	100.23023
2015	103.58575