Year	Percent
1971	7.0461
1972	7.87202
1973	10.86596
1974	10.93482
1975	2.27512
1976	1.13075
1977	0.88324
1978	0.89762
1979	1.65277
1980	0.94122
1981	0.27398
1982	0.28594
1983	0.22066
1984	0.20282
1985	0.13623
1986	0.60753
1987	0.10414
1988	0.10505
1989	0.11912
1990	0.07713
1991	0.04977
1992	0.17687
1993	0.23424
1994	0.45715
1995	0.91691
1996	0.62917
1997	0.49972
1998	0.53805
1999	1.16477
2000	0.85727
2001	0.3309
2002	1.54321
2003	3.06079
2004	7.29717
2005	10.63912
2006	8.99498
2007	6.97916
2008	6.89466
2009	5.19379
2010	4.64968
2011	0.91037
2012	0.88378
2013	0.85867
2014	0.83382
2015	0.81069
2016	0.79824