Year	Percent
1972	103.39861
1973	53.6973
1974	43.18243
1975	36.72278
1976	23.1551
1977	29.20087
1978	11.59525
1979	9.17798
1980	4.67969
1981	5.24215
1982	5.29177
1983	10.68041
1984	14.35842
1985	18.66279
1986	31.76341
1987	46.72174
1988	65.63357
1989	74.88128
1990	75.207
1991	59.66417
1992	48.95067
1993	36.08992
1994	32.86156
1995	34.56048
1996	39.62626
1997	46.26117
1998	42.67981
1999	46.08067
2000	45.74047
2001	41.80802
2002	42.14175
2003	49.76552
2004	48.80266
2005	45.68765
2006	45.8818
2007	48.09117
2008	39.5178
2009	57.13122
2010	58.12688
2011	39.74155
2012	35.03645
2013	33.57582
2014	26.94125
2015	28.00323
2016	23.78863