Year	% of total
1990	40.18349356650287
1991	40.91863822887744
1992	40.08864964525276
1993	39.732282162580745
1994	39.46504545397337
1995	40.87673688568841
1996	41.91274224709183
1997	43.84716098538473
1998	46.33501295597542
1999	48.27794222826999
2000	50.580095356517134
2001	48.74794996270874
2002	49.26905619726225
2003	49.161241503080056
2004	48.765946946187924
2005	49.49679457153417
2006	49.96350556742766
2007	50.08155628559537
2008	50.4251869018821