Year	Percent
1971	20.75838
1972	33.3018
1973	33.19574
1974	16.59872
1975	8.5204
1976	15.51292
1977	14.79271
1978	14.48945
1979	19.16315
1980	6.98364
1981	6.22393
1982	2.02692
1983	2.44565
1984	2.52452
1985	1.55995
1986	2.95088
1987	2.83008
1988	2.32098
1989	2.30751
1990	1.08282
1991	5.15563
1992	4.0046
1993	4.64726
1994	7.67272
1995	23.7375
1996	24.13801
1997	19.85223
1998	24.70058
1999	21.64305
2000	15.16611
2001	11.02967
2002	6.41613
2003	4.58505
2004	14.20349
2005	16.26433
2006	24.12104
2007	36.34279
2008	35.91078
2009	72.72825
2010	197.85679
2011	244.17048
2012	187.41377
2013	161.53107
2014	104.88931
2015	94.88434
2016	100.74772