Year	Percent
1970	69.8419
1971	63.2224
1972	55.25983
1973	53.64879
1974	65.37074
1975	43.44183
1976	40.13236
1977	44.93422
1978	45.72835
1979	35.86514
1980	41.77549
1981	55.22993
1982	66.957
1983	77.97497
1984	102.14798
1985	106.57804
1986	95.37641
1987	98.96566
1988	94.26029
1989	97.51112
1990	92.57125
1991	95.50998
1992	102.72965
1993	102.93319
1994	130.88989
1995	111.24795
1996	110.10902
1997	119.22601
1998	111.68272
1999	94.78976
2000	101.95369
2001	87.23351
2002	76.50353
2003	67.70205
2004	62.50575
2005	52.92082
2006	24.14552
2007	23.34761
2008	21.57313
2009	22.22789
2010	23.93595
2011	23.34506
2012	25.61901
2013	27.83098
2014	25.37699
2015	29.86256
2016	27.94233