Year	Percent
1970	24.96765
1971	26.05881
1972	23.54545
1973	20.81649
1974	19.84087
1975	29.7833
1976	35.38728
1977	51.29992
1978	53.11684
1979	52.54035
1980	45.68666
1981	61.472
1982	72.66237
1983	83.07867
1984	96.8169
1985	111.90869
1986	94.42392
1987	99.25823
1988	85.20461
1989	87.50881
1990	85.35973
1991	71.90629
1992	69.19429
1993	72.24176
1994	66.45439
1995	62.92246
1996	57.54412
1997	61.56645
1998	57.68637
1999	56.41779
2000	54.57689
2001	48.80705
2002	43.53348
2003	35.68455
2004	28.81576
2005	26.18624
2006	26.28808
2007	26.25641
2008	22.70243
2009	26.92505
2010	29.65094
2011	30.02556
2012	35.14222
2013	37.26263
2014	39.9306
2015	43.55394
2016	46.42937