Year % of total 1990 48.06666480231793 1991 47.743557940140015 1992 47.47344961071511 1993 46.92137369434547 1994 46.78909342268864 1995 47.483994530120434 1996 47.98515484655009 1997 46.1335894624765 1998 46.285624207966 1999 46.71178076960569 2000 46.18015855312318 2001 45.651602315036605 2002 45.19374218591627 2003 44.85067498656194 2004 45.28245760661192 2005 45.41763110507441 2006 44.241451950005846 2007 42.984778917391296 2008 42.22923841303888