Year	Percent
1978-01-01	63.9342204997808
1979-01-01	64.1641027338579
1980-01-01	64.1330553200828
1981-01-01	64.0686194738562
1982-01-01	64.1082376492410
1983-01-01	64.5092633397316
1984-01-01	64.1956098166527
1985-01-01	63.9585458596553
1986-01-01	63.7334056800310
1987-01-01	63.6405519218282
1988-01-01	63.9604603375205
1989-01-01	64.5048422489447
1990-01-01	65.1386173403646
1991-01-01	65.7639125900194
1992-01-01	66.0414797435476
1993-01-01	65.7352323116041
1994-01-01	65.3839136554506
1995-01-01	65.1397194567723
1996-01-01	65.2203325387318
1997-01-01	65.5290908702368
1998-01-01	64.8435292688717
1999-01-01	64.1679281315468
2000-01-01	63.9269531397772
2001-01-01	63.5718501039006
2002-01-01	62.8452967345577
2003-01-01	62.7385579982296
2004-01-01	62.9759662937056
2005-01-01	63.4177899990851
2006-01-01	63.9233054846880
2007-01-01	64.4270876538696
2008-01-01	64.4230061406116
2009-01-01	63.6741432083374
2010-01-01	63.7286178760013
2011-01-01	63.9671831765297
2012-01-01	64.1056959468696
2013-01-01	64.9539750872919
2014-01-01	65.6258574303635
2015-01-01	66.1786859783644
2016-01-01	67.1386204312045
2017-01-01	68.0829607245715