Year Percent 1990-01-01 6.238550000000000 1991-01-01 7.186780000000001 1992-01-01 7.048290000000000 1993-01-01 7.388910000000001 1994-01-01 8.837220000000000 1995-01-01 10.654200000000000 1996-01-01 12.996400000000000 1997-01-01 14.854200000000000 1998-01-01 17.394100000000000 1999-01-01 19.369100000000000 2000-01-01 20.799100000000000 2001-01-01 22.480500000000000 2002-01-01 24.679000000000002 2003-01-01 28.222200000000000 2004-01-01 28.917900000000000 2005-01-01 26.572100000000000 2006-01-01 26.927800000000000 2007-01-01 35.982100000000000 2008-01-01 43.533700000000000 2009-01-01 50.486200000000000 2010-01-01 59.686000000000010 2011-01-01 69.460900000000000