Year	% of total
1970	7.814210300396741
1971	7.660065581228093
1972	7.513505820318605
1973	7.376388197910233
1974	7.251861751314167
1975	7.136872874408201
1976	6.958558041447772
1977	6.860247050766409
1978	6.545098949397192
1979	6.413051052574977
1980	6.317023512061487
1981	6.189335358053287
1982	6.074300677221618
1983	5.992383853492343
1984	5.866554680787716
1985	5.732654967720681
1986	5.782499821417714
1987	5.59873522218585
1988	5.5032289931295315
1989	5.374606931564117