Year	Percent
1979-01-01	29.5246144019782
1980-01-01	27.8247605190803
1981-01-01	27.8400438054062
1982-01-01	28.2453754709741
1983-01-01	28.7087633772110
1984-01-01	28.9788126829314
1985-01-01	28.7824799341094
1986-01-01	27.9919708977825
1987-01-01	28.7034581974218
1988-01-01	28.9605344379697
1989-01-01	27.9055260387134
1990-01-01	27.8962113265739
1991-01-01	30.3422674417473
1992-01-01	30.6136317720114
1993-01-01	31.2741599452505
1994-01-01	29.4237404440468
1995-01-01	28.3596774961682
1996-01-01	28.3373110822320
1997-01-01	29.9435180818115
1998-01-01	30.1308646646075
1999-01-01	30.0755769260167
2000-01-01	29.8178813134371
2001-01-01	29.3278164619542
2002-01-01	30.0231272666078
2003-01-01	29.7759433669574
2004-01-01	29.8579296060340
2005-01-01	29.1873954273940
2006-01-01	29.1974190361488
2007-01-01	29.2382424188639
2008-01-01	29.2454697818676
2009-01-01	30.8954126254054
2010-01-01	31.5742564676031
2011-01-01	31.8559022333953
2012-01-01	32.4780808851152
2013-01-01	33.1722506544235
2014-01-01	33.4217936340516
2015-01-01	32.7156748143844
2016-01-01	33.2114813613660
2017-01-01	33.1247617363800