Year	% of total
1970	1.8222860333460984
1971	1.9230234600890719
1972	2.0072628860374886
1973	2.035791371542703
1974	2.0574217137611592
1975	2.090506753184433
1976	2.1395632675837972
1977	2.137623095274725
1978	2.159591897017725
1979	2.1514382784884925
1980	2.181639006575886
1981	2.1187432899318828
1982	2.040470989273319
1983	1.8229547864796536
1984	1.6918568137209031
1985	1.545940415037951
1986	1.4113966178375499
1987	1.273889620680272
1988	1.1389637165205009
1989	1.0064287711818152