Year	% of total
1990	76.66363299162266
1991	75.53863564800955
1992	75.40867189119326
1993	74.30522159694482
1994	74.07633841603699
1995	74.32241973941751
1996	72.41695342214585
1997	71.98675526905375
1998	71.74505928440813
1999	71.5917900397646
2000	71.67441216916683
2001	71.32987534521108
2002	71.6202208674436
2003	71.62823458339706
2004	71.73499945271628
2005	71.96732227573361
2006	71.168901583198
2007	70.6599204089887
2008	69.63630812935546