Year	Percent
1970	45.76581
1971	52.42028
1972	51.84539
1973	49.23931
1974	40.97021
1975	69.03116
1976	75.84944
1977	98.44707
1978	97.77199
1979	100.00329
1980	91.78334
1981	95.91077
1982	97.63738
1983	125.95415
1984	152.45916
1985	223.10245
1986	415.55771
1987	336.59192
1988	202.57134
1989	182.47908
1990	229.75934
1991	232.35575
1992	233.73222
1993	214.62403
1994	199.0646
1995	195.16647
1996	208.18638
1997	164.33986
1998	207.25389
1999	183.71334
2000	168.71441
2001	157.51939
2002	165.07826
2003	144.45567
2004	129.50407
2005	70.91824
2006	20.50016
2007	22.83451
2008	18.65073
2009	25.31488
2010	23.1938
2011	22.86126
2012	23.26992
2013	21.88228
2014	28.25057
2015	42.01579
2016	50.57303