Year	Percent
1968-01-01	0.967995928400275
1969-01-01	0.905704521140287
1970-01-01	0.890446684711907
1971-01-01	0.922466043032010
1972-01-01	1.049635857863850
1973-01-01	1.000607090345390
1974-01-01	1.132514773023100
1975-01-01	1.573348715438740
1976-01-01	1.668028615301410
1977-01-01	1.656353318223550
1978-01-01	1.863756226586230
1979-01-01	1.711818430233640
1980-01-01	1.661030438149470
1981-01-01	1.790049137041620
1982-01-01	1.901723589101440
1983-01-01	2.199330572466730
1984-01-01	2.181866046000900
1985-01-01	2.104607380928130
1986-01-01	2.195326837273360
1987-01-01	2.265923052011890
1988-01-01	1.974897072135450
1989-01-01	1.754118832877270
1990-01-01	1.646345933579840
1991-01-01	1.635418368578850
1992-01-01	1.714416862187340
1993-01-01	2.000763117413640
1994-01-01	2.342311715029980
1995-01-01	2.576414491814910
1996-01-01	2.712152431648530
1997-01-01	2.819063439597160
1998-01-01	3.428506909655950
1999-01-01	3.970851787248240
2000-01-01	4.052364560474680
2001-01-01	4.393500432753170
2002-01-01	4.878045615429880
2003-01-01	4.717135446959110
2004-01-01	4.369942128529020
2005-01-01	4.190214137754270
2006-01-01	3.890761893763860
2007-01-01	3.671527821122260
2008-01-01	3.868697712664650
2009-01-01	4.956959643580860
2010-01-01	4.858602507876810
2011-01-01	4.455324301055560
2012-01-01	4.239906824987910
2013-01-01	4.058939832076390
2014-01-01	3.594522381394550
2015-01-01	3.418759009574000
2016-01-01	3.141547341266480
2017-01-01	2.840762668401940