Year	Percent
1991-01-01	39.37284088
1992-01-01	28.63260841
1993-01-01	20.36466599
1994-01-01	18.93847084
1995-01-01	22.08926392
1996-01-01	24.45429039
1997-01-01	26.67691231
1998-01-01	28.11016464
1999-01-01	28.34008026
2000-01-01	27.73713303
2001-01-01	24.18081665
2002-01-01	24.15342712
2003-01-01	24.31386566
2004-01-01	26.25264359
2005-01-01	29.71191788
2006-01-01	29.62060547
2007-01-01	30.72245598
2008-01-01	31.39291000
2009-01-01	36.50958633
2010-01-01	37.64709091
2011-01-01	37.82357788
2012-01-01	37.33730316
2013-01-01	37.14949799