Year	Percent
1991-01-01	56.8194180767715
1992-01-01	58.9926651451261
1993-01-01	57.1113544886794
1994-01-01	54.8292041472921
1995-01-01	53.8189094162656
1996-01-01	53.1845293011338
1997-01-01	51.9573942537917
1998-01-01	51.0156185680903
1999-01-01	52.7278858299314
2000-01-01	53.5008949303855
2001-01-01	53.3202435516534
2002-01-01	54.0138098011662
2003-01-01	54.5478455959293
2004-01-01	55.7848570350562
2005-01-01	56.6748457044229
2006-01-01	57.0264407085785
2007-01-01	58.1917558389889
2008-01-01	58.4298704685814
2009-01-01	57.4352085552695
2010-01-01	57.6272744513454
2011-01-01	58.2585412382544
2012-01-01	58.7590452674938
2013-01-01	59.2008134057397
2014-01-01	59.2843368948233