Year	Ratio
1974-01-01	0.903770029544830
1975-01-01	0.899330019950867
1977-01-01	0.931779980659485
1978-01-01	0.958249986171722
1979-01-01	0.977379977703094
1980-01-01	0.974449992179871
1981-01-01	0.964079976081848
1982-01-01	0.955540001392365
1983-01-01	0.940349996089935
1984-01-01	0.964860022068024
1985-01-01	0.965269982814789
1986-01-01	0.978779971599579
1987-01-01	0.975740015506744
1988-01-01	0.986370027065277
1989-01-01	0.986259996891022
1990-01-01	0.975099980831146
1991-01-01	0.997139990329742
1994-01-01	0.975629985332489
1998-01-01	0.973940014839172
1999-01-01	0.967209994792938
2000-01-01	0.978359997272491
2001-01-01	0.979070007801056
2002-01-01	0.976320028305054
2003-01-01	0.964789986610413
2004-01-01	0.962499976158142
2005-01-01	0.959860026836395
2006-01-01	0.959500014781952
2007-01-01	0.947220027446747
2008-01-01	0.941690027713776
2009-01-01	0.931150019168854
2010-01-01	0.933149993419647
2011-01-01	0.930999994277954
2012-01-01	0.924390017986298
2013-01-01	0.929139971733093
2014-01-01	0.927969992160797
2015-01-01	0.934509992599487
2016-01-01	0.934379994869232