Year Percent 1998-01-01 25.5364000000000000 1999-01-01 19.1059000000000000 2000-01-01 17.4000000000000000 2001-01-01 16.8000000000000000 2002-01-01 12.0991000000000000 2003-01-01 9.9470900000000000 2004-01-01 8.6540200000000000 2005-01-01 7.1166800000000010 2006-01-01 4.9316699999999996 2007-01-01 3.4747500000000000 2008-01-01 4.8414500000000000 2009-01-01 2.7885600000000000 2010-01-01 3.3817300000000000 2011-01-01 5.0285300000000000 2012-01-01 4.6767800000000000