Year	Percent
1960-01-01	69.2981724634038
1961-01-01	69.1751752349552
1962-01-01	68.3349531787869
1963-01-01	67.0821445038412
1964-01-01	66.1647937004980
1965-01-01	65.7176832227737
1966-01-01	65.8399411120027
1967-01-01	65.9672377047376
1968-01-01	65.9855509017374
1969-01-01	65.5867409716322
1970-01-01	65.4271946933593
1971-01-01	65.0923931704078
1972-01-01	64.5305215328510
1973-01-01	64.8010771629793
1974-01-01	63.8422182195787
1975-01-01	63.2262335102047
1976-01-01	63.1475688237412
1977-01-01	63.3230127482694
1978-01-01	63.5726200972014
1979-01-01	63.6229016977220
1980-01-01	63.4862797781613
1981-01-01	63.5107346756370
1982-01-01	63.5663870438839
1983-01-01	64.0490522804057
1984-01-01	63.7321000600537
1985-01-01	63.3479327590220
1986-01-01	63.1496634496849
1987-01-01	62.9240688752859
1988-01-01	62.9135213021074
1989-01-01	63.1720934263024
1990-01-01	63.5734538528719
1991-01-01	64.0622694859693
1992-01-01	64.1311625553368
1993-01-01	63.8827982123588
1994-01-01	63.6742234608323
1995-01-01	63.4726971613228
1996-01-01	63.5340411668099
1997-01-01	63.7270294006241
1998-01-01	63.3813585061766
1999-01-01	62.9554524611261
2000-01-01	62.5165692041864
2001-01-01	62.0738864012365
2002-01-01	61.2661730308556
2003-01-01	60.8729061895420
2004-01-01	60.5057499814838
2005-01-01	60.4802832966908
2006-01-01	60.4595583556356
2007-01-01	60.4399618944212
2008-01-01	60.2296343532848
2009-01-01	59.9314677971788
2010-01-01	59.7198773909547
2011-01-01	59.3480518220729
2012-01-01	59.1048595984360
2013-01-01	59.3793751076751
2014-01-01	59.5217180330729
2015-01-01	59.6595025280049
2016-01-01	60.0921004013504
2017-01-01	60.5333620285434