Year % of total 1990 45.39191699790755 1991 44.74710505043698 1992 44.916026373235056 1993 44.28636594451932 1994 44.310505011595545 1995 44.24682924958565 1996 43.937940083629684 1997 44.38759884691021 1998 45.19710109318862 1999 45.95289243169267 2000 45.95772304275622 2001 45.74902280868173 2002 46.880159646636336 2003 47.06785675317304 2004 46.91554814074289 2005 47.51193376421496 2006 47.22124283478483 2007 47.47200387027486 2008 47.29198590946727