Year	Percent
1960	1.56562
1961	1.56523
1962	1.57671
1963	1.60549
1964	1.65348
1965	1.71456
1966	1.78141
1967	1.84555
1968	1.90314
1969	1.95071
1970	1.99049
1971	2.0283
1972	2.06659
1973	2.10207
1974	2.13489
1975	2.16505
1976	2.19177
1977	2.21555
1978	2.23772
1979	2.25841
1980	2.27689
1981	2.30082
1982	2.32201
1983	2.3254
1984	2.30705
1985	2.2783
1986	2.23027
1987	2.19652
1988	2.22185
1989	2.32181
1990	2.46155
1991	2.6092
1992	2.71023
1993	2.7307
1994	2.65117
1995	2.50467
1996	2.3419
1997	2.19647
1998	2.06214
1999	1.94836
2000	1.84892
2001	1.75722
2002	1.66054
2003	1.55215
2004	1.4279
2005	1.2987
2006	1.16452
2007	1.05159
2008	0.99074
2009	0.99685
2010	1.04916
2011	1.11872
2012	1.17424
2013	1.20567
2014	1.2003
2015	1.169
2016	1.13289
2017	1.10565