Year	Percent
1960	9.19482
1961	9.77709
1962	8.87316
1963	9.3798
1964	9.86634
1965	11.16799
1966	12.39599
1967	12.76514
1968	13.88681
1969	12.81727
1970	12.57658
1971	12.60498
1972	12.91961
1973	14.77514
1974	14.96835
1975	14.95528
1976	14.91593
1977	13.68077
1978	13.17745
1979	10.51448
1980	9.03893
1981	11.88868
1982	12.5495
1983	13.18452
1984	15.53677
1985	12.71784
1986	14.55682
1987	13.97006
1988	12.9321
1989	15.88649
1990	16.87542
1991	12.90316
1992	13.04743
1993	13.60644
1994	11.72822
1995	13.34297
1996	12.44695
1997	13.6671
1998	12.87216
1999	12.21439
2000	10.91266
2001	13.08316
2002	14.25984
2003	23.41351
2004	45.97529
2005	9.23916
2006	10.03454
2007	9.70506
2008	10.46866
2009	13.20989
2010	11.96806
2011	12.609
2012	12.93363
2013	13.32972
2014	14.51112
2015	13.60267
2016	14.64447
2017	14.62032