Year	Percent
1961	1.50215
1962	1.53731
1963	1.46037
1964	1.45875
1965	1.59085
1966	1.54227
1967	1.55003
1968	1.54622
1969	1.50725
1970	1.35124
1971	1.31657
1972	1.48819
1973	1.52386
1974	1.67069
1975	1.63715
1976	1.88021
1977	2.3072
1978	2.41985
1979	2.92724
1980	2.76892
1981	2.97845
1984	1.87316
1985	1.78005
1986	1.55194
1987	1.42904
1988	1.34718
1989	1.21087
1990	1.23151
1991	1.29635
1992	0.76992
1993	1.12232
1994	0.92647
1995	0.85989
1996	1.23763
1997	1.48191
1998	1.34893
1999	1.21023
2000	1.21751
2001	1.43585
2002	1.31316
2003	1.32476
2004	1.24823
2005	1.07209
2006	0.97755
2007	1.11587
2008	1.09712
2009	0.83005
2010	0.65204
2011	0.72771
2012	0.69191
2013	0.67798
2014	0.6528
2015	0.60514
2016	0.59434
2017	0.58529