Year	Percent
1978-01-01	65.4061581713077
1979-01-01	65.5427387895809
1980-01-01	65.4569673540557
1981-01-01	65.5191502639028
1982-01-01	65.6636339935133
1983-01-01	66.2775404373305
1984-01-01	66.0015600348469
1985-01-01	65.6933414609564
1986-01-01	65.5651741768996
1987-01-01	65.5154352541406
1988-01-01	65.6320091766522
1989-01-01	66.0133053795617
1990-01-01	66.5457121527865
1991-01-01	67.1871416837901
1992-01-01	67.5154011886247
1993-01-01	67.4393258081538
1994-01-01	67.3476964344868
1995-01-01	67.2804774774407
1996-01-01	67.5061799033225
1997-01-01	67.8527553555968
1998-01-01	67.6482336401581
1999-01-01	67.3549577992461
2000-01-01	67.1368536802410
2001-01-01	66.9780657739510
2002-01-01	66.4509958814333
2003-01-01	66.2688989561244
2004-01-01	66.1434100812843
2005-01-01	66.3970330553720
2006-01-01	66.7200573383403
2007-01-01	67.0457958409747
2008-01-01	67.1391193129641
2009-01-01	67.1323909154654
2010-01-01	67.1858396552218
2011-01-01	67.0720284512296
2012-01-01	67.0643488204423
2013-01-01	67.7276674736998
2014-01-01	68.1084123791404
2015-01-01	68.5160819712206
2016-01-01	69.3378195948359
2017-01-01	70.0978154427027