Year	% of total
1990	74.51167353503851
1991	73.12071956330121
1992	72.07047226254491
1993	70.83452483265192
1994	70.11902062865407
1995	69.89979934942009
1996	69.39338689890093
1997	69.42587253257784
1998	70.13880852667558
1999	70.07780393299255
2000	69.94173910595411
2001	68.86621446752675
2002	69.50443041205814
2003	69.70369526700024
2004	69.2392122078234
2005	69.64677205204816
2006	68.62823532716502
2007	68.58074212872418
2008	68.48613451134801