Year	Percent
1970	30.21301
1971	28.38965
1972	28.03167
1973	35.19521
1974	40.13318
1975	40.74701
1976	44.81082
1977	38.25736
1978	42.48743
1979	45.27552
1980	48.08473
1981	48.61771
1982	54.52035
1983	62.67762
1984	58.64604
1985	70.56254
1986	65.76996
1987	75.20136
1988	72.3342
1989	73.25847
1990	85.96928
1991	95.82897
1992	87.8233
1993	131.89928
1994	104.98966
1995	83.76172
1996	57.64597
1997	49.94767
1998	48.87199
1999	51.29293
2000	48.89039
2001	42.81091
2002	46.80582
2003	45.57118
2004	43.35286
2005	34.62991
2006	25.94368
2007	23.69533
2008	21.35698
2009	23.12054
2010	22.20105
2011	24.2198
2012	23.74139
2013	25.38845
2014	28.01286
2015	31.32998
2016	31.96356