Year	Percent
1960	1.16841
1961	1.07584
1962	0.98839
1963	0.93171
1964	1.28009
1965	1.22911
1966	1.18182
1967	1.13712
1968	1.08545
1969	1.06825
1970	1.36929
1971	1.47002
1972	1.83601
1973	1.68338
1974	1.59886
1975	1.90391
1976	1.75816
1977	1.90476
1978	2.26962
1979	2.23955
1980	2.22136
1981	2.14577
1982	2.30756
1983	2.27494
1984	2.44049
1985	2.58277
1986	2.77012
1987	2.95003
1988	2.85375
1989	2.6708
1990	2.20148
1991	1.54469
1993	1.15783
2000	0.72993
2001	0.82261
2002	0.80919
2003	0.99826
2004	0.68269
2005	0.64148
2006	0.69243
2007	0.77601
2008	0.95398
2009	1.07491
2010	1.07446
2011	1.13131
2012	1.14602
2013	1.54642
2014	1.55525
2015	1.54989
2016	1.64186
2017	1.57823