Year	Ratio
1971-01-01	0.356959998607636
1972-01-01	0.391510009765625
1973-01-01	0.444819986820221
1974-01-01	0.472350001335144
1975-01-01	0.546840012073517
1976-01-01	0.624849975109100
1977-01-01	0.674229979515076
1978-01-01	0.738969981670380
1981-01-01	1.052139997482300
1983-01-01	1.080279946327210
1984-01-01	1.119330048561100
1986-01-01	1.288079977035520
1989-01-01	1.309769988060000
1990-01-01	1.316969990730290
1991-01-01	1.386160016059880
1992-01-01	1.452059984207150
1993-01-01	1.396460056304930
1994-01-01	1.419170022010800
1995-01-01	1.401620030403140
1996-01-01	1.477399945259090
1997-01-01	1.460630059242250
1998-01-01	1.548449993133540
1999-01-01	1.687929987907410
2000-01-01	1.660730004310610
2001-01-01	1.710500001907350
2002-01-01	1.749340057373050
2003-01-01	1.791380047798160
2004-01-01	1.874199986457820
2005-01-01	1.922170042991640
2006-01-01	1.886620044708250
2007-01-01	1.877150058746340
2008-01-01	1.896669983863830
2009-01-01	1.870149970054630
2010-01-01	1.788769960403440
2011-01-01	1.686579942703250
2012-01-01	1.711249947547910
2013-01-01	1.707939982414250
2014-01-01	1.741909980773930
2015-01-01	1.792469978332520