Year	Percent
1960	40.36124
1961	41.6725
1962	40.08584
1963	37.94701
1964	60.27344
1965	63.87472
1966	43.13596
1967	41.04439
1968	40.30488
1969	36.94825
1970	39.74034
1971	39.47838
1972	37.09169
1973	39.10966
1974	43.38772
1975	42.63326
1976	36.92134
1977	36.37324
1978	36.15137
1979	38.30012
1980	42.85157
1981	38.73243
1982	34.12298
1983	30.13884
1984	35.46844
1985	38.01493
1986	39.14742
1987	39.04341
1988	37.65939
1989	38.1834
1990	40.67708
1991	41.50909
1992	54.03266
1993	51.58587
1994	59.86351
1995	67.18912
1996	60.90156
1997	66.04083
1998	75.16438
1999	58.51549
2000	56.62218
2001	43.11398
2002	59.33351
2003	59.01259
2004	70.46261
2005	72.97729
2006	78.98754
2007	93.5383
2008	116.62923
2009	59.95307
2010	69.01329
2011	65.39784
2012	58.15296
2013	50.5262
2014	50.76051
2015	44.45533
2016	42.23168
2017	44.22001