Year	Percent
1992-01-01	39.9981
1993-01-01	43.7195
1994-01-01	49.3858
1995-01-01	52.5292
1996-01-01	52.7577
1997-01-01	53.8173
1998-01-01	58.0476
1999-01-01	58.7232
2000-01-01	57.0594
2001-01-01	53.0372
2002-01-01	48.1169
2003-01-01	46.6991
2004-01-01	41.5204
2005-01-01	34.9232
2006-01-01	32.7031
2007-01-01	35.4143
2008-01-01	35.3997
2009-01-01	36.5119
2010-01-01	31.5934
2011-01-01	24.0197