Year	Percent
1979-01-01	39.2435864038070
1980-01-01	38.7058324743654
1981-01-01	38.8642136483002
1982-01-01	39.2188404703554
1983-01-01	39.5629758179908
1984-01-01	39.4499201381443
1985-01-01	39.1962178679601
1986-01-01	38.1136896336785
1987-01-01	38.0419168846462
1988-01-01	37.6210171615905
1989-01-01	36.8420171460101
1990-01-01	36.2539924343420
1991-01-01	36.8612815509728
1992-01-01	37.1366127140176
1993-01-01	37.5497104124444
1994-01-01	37.0665589015218
1995-01-01	36.4589522018094
1996-01-01	36.4799076779716
1997-01-01	36.8765496542960
1998-01-01	37.0026552286608
1999-01-01	37.2367236644369
2000-01-01	36.8625719712840
2001-01-01	36.7023038689802
2002-01-01	36.6365761473964
2003-01-01	36.4134823984331
2004-01-01	36.5411275408587
2005-01-01	35.6029180290491
2006-01-01	35.2449100613806
2007-01-01	34.8251145589798
2008-01-01	34.5192700227127
2009-01-01	34.5682200446381
2010-01-01	34.6102483044288
2011-01-01	34.5773937834565
2012-01-01	34.8443515072007
2013-01-01	35.0544480257527
2014-01-01	35.2863771262353
2015-01-01	34.9916256633321
2016-01-01	35.1204414895055
2017-01-01	34.8306713708775