Year Percent 1990-01-01 4.23727 1991-01-01 6.09053 1992-01-01 10.47970 1993-01-01 19.84360 1994-01-01 26.48620 1995-01-01 28.02250 1996-01-01 32.27220 1997-01-01 35.27650 1998-01-01 37.73980 1999-01-01 35.80090 2000-01-01 30.62750 2001-01-01 27.27050 2002-01-01 24.12780 2003-01-01 20.10050 2004-01-01 15.49050 2005-01-01 11.48250 2006-01-01 9.14631 2007-01-01 9.94765 2008-01-01 9.59165 2009-01-01 10.64730 2010-01-01 12.63200 2011-01-01 12.24710