Year	% of total
1970	56.73519081935176
1971	55.511061924949146
1972	54.4257482290204
1973	53.593567200724934
1974	55.429055961758635
1975	55.75868280876068
1976	56.88776523742105
1977	55.66231523521113
1978	56.50954796701877
1979	56.54415343828217
1980	56.41140265915294
1981	58.04393824260846
1982	55.73037286053945
1983	54.43726984932877
1984	54.27805698354512
1985	54.83498946495049
1986	56.502639393696185
1987	55.35105409419769
1988	53.90421376345203
1989	52.69694215147348
1990	70.23498694516971
1991	71.54362416107382
1992	70.3551912568306
1993	68.65021770682148
1994	69.27453769559034
1995	68.47507331378299
1996	67.83707865168539
1997	67.73722627737226
1998	67.76119402985074
1999	67.26190476190477
2000	68.37349397590361
2001	68.23161189358372
2002	68.68217054263566
2003	69.02927580893683
2004	68.14449917898193
2005	66.890756302521
2006	66.13756613756614
2007	65.44789762340037
2008	67.49116607773851