Year	Percent
1970	1.87213
1971	1.84267
1972	1.76285
1973	1.76067
1974	1.69194
1975	1.72759
1976	1.76233
1977	1.71585
1978	1.66512
1979	1.65536
1980	1.55582
1981	1.81892
1982	1.99052
1983	1.89068
1984	1.74022
1985	1.33984
1986	1.21782
1987	1.25003
1988	1.2848
1989	1.33369
1990	1.47457
1991	1.51455
1992	1.53261
1993	1.32612
1994	1.31034
1995	1.25164
1996	1.22484
1997	1.30124
1998	1.39651
1999	1.44385
2000	1.32475
2001	1.29036
2002	1.33851
2003	1.38381
2004	1.4016
2005	1.34486
2006	1.43111
2007	1.45214
2008	1.48607
2009	1.46812
2010	1.4988
2011	1.30693
2012	1.33895
2013	1.32867
2014	1.25283
2015	1.2451
2016	1.32147
2017	1.31659