Year	Percent
1971	12.61749
1972	14.31401
1973	15.87333
1974	20.67226
1975	9.03865
1976	5.49508
1977	5.60136
1978	6.25053
1979	22.44534
1980	29.40994
1981	20.07596
1982	18.29058
1983	16.49879
1984	16.72547
1985	19.01119
1986	14.90464
1987	7.77097
1988	6.60129
1989	8.50877
1990	9.31461
1991	14.8549
1992	16.92472
1993	16.56468
1994	27.89911
1995	27.99358
1996	37.85332
1997	38.03573
1998	32.31366
1999	30.82184
2000	30.08862
2001	32.39271
2002	34.19877
2003	33.9517
2004	39.89821
2005	48.01619
2006	59.53713
2007	86.18739
2008	89.98116
2009	88.86106
2010	104.88903
2011	108.66661
2012	117.5901
2013	115.77964
2014	102.05676
2015	93.40967
2016	88.91864