Year	Percent
1968-01-01	0.879881561323203
1969-01-01	0.839070636210976
1970-01-01	0.766276180224083
1971-01-01	0.891341712377693
1972-01-01	1.000194592733560
1973-01-01	0.917860372655948
1974-01-01	1.107632102375020
1975-01-01	1.521008928768020
1976-01-01	1.440945848910100
1977-01-01	1.591527753912920
1978-01-01	1.772174148660190
1979-01-01	1.733206939499880
1980-01-01	1.759632504120910
1981-01-01	1.840316910005620
1982-01-01	1.934612027310700
1983-01-01	2.325405222724070
1984-01-01	2.377168219875610
1985-01-01	2.291037697679140
1986-01-01	2.408780685692700
1987-01-01	2.424707324664390
1988-01-01	2.212370505787080
1989-01-01	1.971218439506870
1990-01-01	1.835790348531180
1991-01-01	1.851490240739630
1992-01-01	1.891435378198250
1993-01-01	2.160069840139980
1994-01-01	2.506400612242810
1995-01-01	2.702107050323130
1996-01-01	2.793209917327060
1997-01-01	2.908129438718830
1998-01-01	3.466331529652670
1999-01-01	3.897645585459330
2000-01-01	3.957388158933330
2001-01-01	4.189600957670730
2002-01-01	4.604506026493640
2003-01-01	4.439736031764690
2004-01-01	3.946458025481780
2005-01-01	3.815093476849930
2006-01-01	3.471686569532920
2007-01-01	3.312695712765150
2008-01-01	3.523568261125520
2009-01-01	4.398968576175990
2010-01-01	4.184432050606060
2011-01-01	3.853061599146520
2012-01-01	3.691955284551800
2013-01-01	3.446934565809820
2014-01-01	3.170174665148400
2015-01-01	2.905307357737730
2016-01-01	2.666389023903050
2017-01-01	2.463096245555320