Year	% of total
1970	77.82072836676247
1971	77.78487770893992
1972	77.77239176286905
1973	77.82976815695723
1974	77.48645922851189
1975	77.58652993763866
1976	77.6330766481059
1977	77.86338240928575
1978	77.71370452217423
1979	78.03061929234681
1980	78.18415702868988
1981	78.08384521618149
1982	78.19525662887469
1983	78.25637618788824
1984	78.15494555347148
1985	78.10099956964343
1986	78.12646658590468
1987	78.12445981834675
1988	78.09515774296035
1989	78.20054133611298
1990	53.316326530612244
1991	53.53788353162179
1992	53.233830845771145
1993	52.93390982087709
1994	52.81173594132029
1995	52.723970944309926
1996	55.125284738041
1997	55.22303783173348
1998	57.31837606837607
1999	54.44255800792304
2000	57.702349869451695
2001	53.511317469529885
2002	50.74626865671642
2003	57.61517615176152
2004	54.8801870251315
2005	56.49942987457241
2006	55.43840177580466
2007	54.82832618025751
2008	54.95403472931562