Year	% of total
1990	85.88915488413113
1991	85.95626864905883
1992	86.20049685936928
1993	86.04770424268398
1994	86.31204005928033
1995	86.08800879879385
1996	85.68673878816384
1997	84.95821899664331
1998	84.5951651349275
1999	84.16787498143202
2000	83.03616958060091
2001	83.02041893308717
2002	83.00400225890772
2003	82.78512336201247
2004	82.60571321560693
2005	82.43976408417613
2006	81.87271349537315
2007	81.85260705926764
2008	81.48946846622167