Year Years 1990 76.8 1991 77.1 1992 77.3 1993 77.6 1994 77.8 1995 78 1996 78.1 1997 78.2 1998 78.3 1999 78.5 2000 78.7 2001 78.9 2002 79.2 2003 79.5 2004 79.7 2005 80.1 2006 80.4 2007 80.6 2008 80.7 2009 80.8 2010 80.9 2011 81.1 2012 81.3 2013 81.4