Year	Percent
1970	12.47114
1971	11.10144
1972	8.2805
1973	6.64903
1974	5.53325
1975	4.33709
1976	3.3896
1977	4.65013
1978	10.39264
1979	10.96775
1980	12.0311
1981	15.98518
1982	22.51164
1983	28.96543
1984	34.99151
1985	43.79525
1986	43.44733
1987	44.18987
1988	35.58235
1989	34.929
1990	38.52052
1991	41.66063
1992	63.74297
1993	67.2838
1994	68.02206
1995	73.52992
1996	60.53779
1997	60.07916
1998	76.42625
1999	66.69828
2000	60.71473
2001	56.68641
2002	65.52391
2003	83.59133
2004	89.70982
2005	81.10951
2006	95.6799
2007	115.82591
2008	143.81893
2009	75.29706
2010	69.96121
2011	65.33026
2012	65.5857
2013	57.31607
2014	54.06091
2015	56.72103
2016	57.00867