Year	Percent
1990-01-01	38.418000000000000
1991-01-01	46.746500000000000
1992-01-01	31.684500000000000
1993-01-01	22.843800000000000
1994-01-01	17.745300000000000
1995-01-01	17.027000000000000
1996-01-01	17.615100000000000
1997-01-01	17.304800000000000
1998-01-01	18.976300000000000
1999-01-01	19.663700000000000
2000-01-01	20.732900000000000
2001-01-01	24.521500000000000
2002-01-01	28.148100000000000
2003-01-01	30.726999999999997
2004-01-01	34.575300000000000
2005-01-01	36.099200000000000
2006-01-01	35.099900000000000
2007-01-01	36.143400000000000
2008-01-01	31.893500000000000
2009-01-01	34.045300000000000
2010-01-01	40.041000000000000
2011-01-01	37.177100000000000