Year	Percent
1979-01-01	70.7198276950747
1980-01-01	71.1904935093398
1981-01-01	71.3914191972097
1982-01-01	70.6397914209270
1983-01-01	68.8837643587239
1984-01-01	70.0262896918566
1985-01-01	71.0611854545016
1986-01-01	72.6716676505295
1987-01-01	72.9464328427628
1988-01-01	74.2064643893330
1989-01-01	75.5411008331062
1990-01-01	76.0341453946871
1991-01-01	74.2669156220833
1992-01-01	73.2890244364468
1993-01-01	72.8474657196170
1994-01-01	73.6044013014131
1995-01-01	75.0440636528918
1996-01-01	74.9888609294005
1997-01-01	74.9045159938183
1998-01-01	75.1391244240288
1999-01-01	75.4913696709064
2000-01-01	76.2282884405314
2001-01-01	76.2802237917711
2002-01-01	76.7261054835171
2003-01-01	77.2747003124870
2004-01-01	77.4500740113893
2005-01-01	78.7646948700885
2006-01-01	79.1782915346701
2007-01-01	79.9266610479693
2008-01-01	80.3108630374544
2009-01-01	79.1504192030874
2010-01-01	79.4622705116543
2011-01-01	79.8023131014713
2012-01-01	79.4497196990362
2013-01-01	79.1426433806785
2014-01-01	78.7959062727354
2015-01-01	79.3041504460611
2016-01-01	79.6832543899776
2017-01-01	80.2230299328038