Year	Percent
1979-01-01	30.0660652439157
1980-01-01	30.9766078549674
1981-01-01	32.3933937617782
1982-01-01	34.2999011990520
1983-01-01	36.9222198964150
1984-01-01	37.8155415350946
1985-01-01	38.6242022193588
1986-01-01	38.0551668150615
1987-01-01	38.6303968319592
1988-01-01	38.3318127580622
1989-01-01	37.3703645840818
1990-01-01	37.1666498446527
1991-01-01	38.2640778663851
1992-01-01	38.4401159215258
1993-01-01	39.6713710155845
1994-01-01	38.5995848269770
1995-01-01	38.5878347895377
1996-01-01	39.5109156352503
1997-01-01	39.7666468948037
1998-01-01	39.4401759450305
1999-01-01	39.5006710475769
2000-01-01	39.1534399710930
2001-01-01	39.4621252084555
2002-01-01	38.0139282668131
2003-01-01	36.5154704182248
2004-01-01	35.3575151373671
2005-01-01	33.8011950062567
2006-01-01	32.7114469853109
2007-01-01	32.3491610032766
2008-01-01	32.3586673772380
2009-01-01	30.7071172329470
2010-01-01	28.7783353431978
2011-01-01	28.3347650713315
2012-01-01	28.2504535728946
2013-01-01	27.8915811001547
2014-01-01	27.8341002163631
2015-01-01	27.2205743463243
2016-01-01	28.0595871032098
2017-01-01	27.2416103363486