Year	Percent
1960	1.70199
1961	1.65773
1962	1.538
1963	1.43916
1964	1.38905
1965	1.25017
1966	1.15489
1967	1.08888
1968	0.99846
1969	0.97724
1970	1.165
1971	1.26433
1972	1.07052
1973	0.95448
1974	0.91366
1975	0.98599
1976	0.95022
1977	1.00577
1978	1.05957
1979	1.10358
1980	0.95959
1981	0.98142
1982	0.95332
1983	0.91438
1984	0.86582
1985	0.88613
1986	0.92416
1987	0.89383
1988	0.908
1989	0.94441
1990	1.12965
1991	1.33626
1992	1.38689
1993	1.31868
1994	1.2263
1995	1.19079
1996	1.16341
1997	1.20396
1998	1.16571
1999	1.14834
2000	1.11277
2001	0.98974
2002	0.9278
2003	0.85948
2004	0.92548
2005	0.92171
2006	0.96425
2007	0.95106
2008	0.94587
2009	0.87665
2010	0.83326
2011	0.74265
2012	0.75091
2013	0.71125
2014	0.75231
2015	0.75581
2016	0.73431
2017	0.71273