Year	Percent
1970	4.88498
1971	6.0059
1972	7.39995
1973	6.88096
1974	9.21703
1975	11.01846
1976	12.57238
1977	13.4207
1978	34.9368
1979	30.78616
1980	34.96948
1981	48.76325
1982	49.356
1983	55.16629
1984	69.5496
1985	87.49713
1986	76.50729
1987	76.07186
1988	76.08867
1989	69.53211
1990	72.5204
1991	66.69953
1992	66.91429
1993	99.49287
1994	100.64338
1995	87.6053
1996	79.33149
1997	87.43895
1998	82.1418
1999	85.88461
2000	96.56289
2001	84.59132
2002	86.23215
2003	79.57485
2004	65.09236
2005	57.89114
2006	21.02577
2007	25.52782
2008	17.79145
2009	23.45063
2010	27.307
2011	35.14108
2012	34.5463
2013	35.55243
2014	32.96315
2015	41.2229
2016	43.49081