Year	Percent
1970	33.79867
1971	40.68482
1972	57.13339
1973	59.55169
1974	37.23813
1975	44.03232
1976	43.60295
1977	55.54694
1978	69.95359
1979	64.54639
1980	39.26369
1981	32.13015
1982	30.27747
1983	29.54788
1984	27.54921
1985	38.9536
1986	61.56336
1987	86.17962
1988	79.98549
1989	84.781
1990	74.63676
1991	87.08545
1992	79.1467
1993	103.0936
1994	112.96584
1995	101.56836
1996	87.43253
1997	92.83843
1998	111.59053
1999	97.80043
2000	91.39509
2001	78.28541
2002	72.27363
2003	65.18704
2004	62.19734
2005	45.83901
2006	47.79426
2007	45.80135
2008	16.12293
2009	21.73774
2010	20.23577
2011	17.83477
2012	18.56444
2013	27.21316
2014	24.70104
2015	38.70019
2016	38.67963