Year	Percent
1971	8.12058
1972	8.7198
1973	11.80383
1974	26.65557
1975	18.22783
1976	15.20062
1977	17.20979
1978	14.09252
1979	20.04268
1980	19.87157
1981	12.96756
1982	16.43937
1983	12.21671
1984	12.0824
1985	10.05458
1986	9.05308
1987	8.9361
1988	9.45635
1989	13.31836
1990	11.69184
1991	10.15566
1992	11.06767
1993	13.00307
1994	15.95726
1995	18.721
1996	24.60204
1997	25.51284
1998	21.37318
1999	22.02761
2000	20.07131
2001	23.87362
2002	17.45225
2003	18.67028
2004	20.1912
2005	25.72083
2006	50.95335
2007	103.91734
2008	134.95451
2009	147.56229
2010	167.59613
2011	193.12122
2012	208.96084
2013	175.93673
2014	169.66453
2015	131.63025
2016	91.26956