Year Percent 1995 20.31 1996 20.44 1997 20.36 1998 20.48 1999 20.55 2000 20.62 2001 20.62 2002 20.34 2003 21.08 2004 21.18 2005 21.16 2006 21.26 2007 21.66 2008 22.3 2009 22.07 2010 22.15