Year	Percent
1970	14.19272
1971	15.90441
1972	17.06288
1973	15.20092
1974	11.01819
1975	12.9473
1976	13.50361
1977	22.8439
1978	34.8927
1979	33.51297
1980	34.99292
1981	36.62685
1982	40.77909
1983	46.73196
1984	52.33143
1985	54.6461
1986	65.79992
1987	81.7353
1988	90.5009
1989	89.54574
1990	86.69721
1991	78.8917
1992	71.50174
1993	78.10379
1994	83.17084
1995	72.32218
1996	72.09076
1997	67.6456
1998	69.16779
1999	104.47823
2000	101.16123
2001	76.70475
2002	71.49517
2003	64.33652
2004	59.1681
2005	51.28794
2006	45.18184
2007	42.9102
2008	31.57463
2009	21.79726
2010	21.96132
2011	20.3754
2012	18.93302
2013	19.85875
2014	23.98098
2015	27.68936
2016	35.53147