Year	Ratio
1971-01-01	0.617150008678436
1972-01-01	0.602540016174316
1973-01-01	0.633989989757538
1974-01-01	0.659340023994446
1975-01-01	0.658389985561371
1976-01-01	0.651839971542358
1977-01-01	0.667280018329620
1978-01-01	0.694710016250610
1979-01-01	0.716090023517609
1980-01-01	0.747850000858307
1981-01-01	0.758800029754639
1983-01-01	0.810519993305206
1984-01-01	0.827390015125275
1985-01-01	0.852880001068115
1986-01-01	0.882480025291443
1987-01-01	0.907090008258820
1988-01-01	0.924700021743774
1989-01-01	0.944350004196167
1990-01-01	0.961799979209900
1991-01-01	0.938839972019196
1992-01-01	1.016510009765630
1993-01-01	1.058500051498410
1994-01-01	1.098790049552920
1995-01-01	1.141540050506590
1996-01-01	1.163409948349000
1997-01-01	1.213569998741150
1998-01-01	1.334169983863830
1999-01-01	1.274270057678220
2000-01-01	1.294849991798400
2001-01-01	1.323909997940060
2002-01-01	1.340499997138980
2003-01-01	1.344179987907410
2004-01-01	1.345649957656860
2005-01-01	1.368460059165950
2006-01-01	1.392050027847290
2007-01-01	1.406839966773990
2008-01-01	1.416039943695070
2009-01-01	1.429730057716370
2010-01-01	1.425590038299560
2011-01-01	1.428419947624210
2012-01-01	1.419929981231690
2013-01-01	1.395449995994570
2014-01-01	1.380689978599550
2015-01-01	1.357059955596920