Year	Percent
1977-01-01	43.6817470409458
1978-01-01	43.7401594064888
1979-01-01	43.7491904413852
1980-01-01	44.3073789723235
1981-01-01	44.9829889017147
1982-01-01	44.9476951280975
1983-01-01	45.5000258413135
1984-01-01	45.7600675701238
1985-01-01	45.8374693326466
1986-01-01	45.9621905531468
1987-01-01	45.6042932318844
1988-01-01	45.4361945440905
1989-01-01	44.4819593005132
1990-01-01	44.1333838163289
1991-01-01	44.5064618093473
1992-01-01	43.7636833380481
1993-01-01	43.6231551119247
1994-01-01	43.2386458524044
1995-01-01	42.8028236275994
1996-01-01	42.1378956720086
1997-01-01	41.1119997215704
1998-01-01	40.7304645379952
1999-01-01	40.6792421066915
2000-01-01	40.7491734929666
2001-01-01	39.6168811367254
2002-01-01	38.0969642548570
2003-01-01	37.5664458680866
2004-01-01	37.7115090196329
2005-01-01	37.0839322879919
2006-01-01	36.3067502801921
2007-01-01	36.2200967017876
2008-01-01	35.4622632754613
2009-01-01	35.0838270556007
2010-01-01	35.0773900243055
2011-01-01	35.7489027117852
2012-01-01	35.5150230099901
2013-01-01	35.6330769833046
2014-01-01	35.8665351341650
2015-01-01	36.0642612473250
2016-01-01	35.9308641622406
2017-01-01	35.4801936242313