Year	Ratio
1970-01-01	0.41066
1971-01-01	0.40624
1972-01-01	0.39946
1973-01-01	0.40284
1974-01-01	0.40899
1975-01-01	0.41607
1976-01-01	0.42107
1977-01-01	0.42229
1978-01-01	0.41160
1979-01-01	0.40288
1980-01-01	0.39942
1981-01-01	0.39499
1982-01-01	0.39759
1983-01-01	0.40012
1984-01-01	0.40262
1985-01-01	0.40734
1986-01-01	0.40469
1987-01-01	0.40929
1988-01-01	0.41002
1989-01-01	0.40986
1990-01-01	0.41544
1991-01-01	0.41084
1992-01-01	0.41330
1993-01-01	0.41488
1994-01-01	0.41524
1995-01-01	0.41192
1996-01-01	0.41189
1997-01-01	0.41279
1998-01-01	0.41704
1999-01-01	0.42052
2000-01-01	0.43097
2001-01-01	0.42051
2002-01-01	0.42541
2003-01-01	0.42877
2004-01-01	0.43602
2005-01-01	0.45486
2006-01-01	0.45898
2007-01-01	0.46446
2008-01-01	0.47300
2009-01-01	0.48040
2010-01-01	0.49433
2011-01-01	0.50854
2012-01-01	0.53207
2013-01-01	0.53730
2014-01-01	0.54335
2015-01-01	0.55487
2016-01-01	0.55408