Year	% of total
1970	80.8058151305606
1971	81.00699013686221
1972	80.7156958853232
1973	80.37043972663322
1974	80.13804908979539
1975	80.00644384811355
1976	79.50362065333876
1977	79.07781144441154
1978	79.14461930011194
1979	79.08405152768397
1980	79.05150753994754
1981	78.80656072435097
1982	78.49533814849461
1983	78.25115125195575
1984	78.10174835185853
1985	77.54943260476365
1986	76.95730562006685
1987	76.68176536848851
1988	71.69733018899599
1989	69.8878586764879
1990	61.29032258064516
1991	61.065573770491795
1992	59.49656750572082
1993	58.536585365853654
1994	65.47945205479452
1995	67.15542521994135
1996	69.30379746835443
1997	68.370607028754
1998	69.93243243243244
1999	73.68421052631578
2000	72.82229965156795
2001	71.52542372881356
2002	73.15436241610739
2003	72.29299363057325
2004	74.30340557275542
2005	75.80174927113703
2006	77.03081232492998
2007	78.41530054644808
2008	81.17359413202934