Year	% of total
1990	83.019653238894
1991	82.79996198065363
1992	82.19858278422915
1993	81.44464706690091
1994	81.32155071734842
1995	81.75237597804009
1996	81.61015595263726
1997	80.01962558897542
1998	79.99108172793997
1999	81.04128278517874
2000	80.07634190925295
2001	80.18342192611613
2002	80.17609561993375
2003	78.32055486423475
2004	78.79039111122414
2005	78.10260531172702
2006	78.06241711951317
2007	78.31693502931988
2008	77.13032825423724