Year	Percent
1960	29.52673
1961	32.10405
1962	29.90839
1963	31.11562
1964	30.96396
1965	32.28257
1966	34.53633
1967	35.10145
1968	36.02141
1969	34.61977
1970	33.05221
1971	32.28546
1972	30.89894
1973	33.97871
1974	38.06199
1975	38.17625
1976	41.36052
1977	44.16394
1978	44.64708
1979	44.45778
1980	44.30915
1981	43.3233
1982	42.98509
1983	46.8981
1984	53.24646
1985	53.97323
1986	49.04041
1987	52.37711
1988	55.52593
1989	58.85776
1990	54.6408
1991	55.51537
1992	58.33562
1993	63.29119
1994	67.87876
1995	73.43206
1996	74.81834
1997	77.1532
1998	84.4339
1999	86.60794
2000	94.48989
2001	95.32443
2002	90.47764
2003	80.85148
2004	80.53675
2005	79.58316
2006	79.00152
2007	80.78254
2008	84.11994
2009	93.23877
2010	103.11091
2011	103.11961
2012	106.89017
2013	106.03798
2014	112.97903
2015	124.64256
2016	121.58236
2017	120.01253