Year	% of total
1970	4.5341355993328225
1971	4.821937640917935
1972	4.5924460235036895
1973	4.630627548037869
1974	4.35178867453972
1975	4.1125331520649
1976	4.292143882443471
1977	4.323083142696419
1978	4.384416864298935
1979	4.319124651572204
1980	4.323367977353968
1981	4.323162347309343
1982	4.098918053865722
1983	4.352533288112599
1984	4.604619678385749
1985	4.687862904057595
1986	4.519864925767117
1987	4.322780828418412
1988	4.766745505523333
1989	5.125309540975726
1990	10.084033613445378
1991	10.69182389937107
1992	10.865191146881289
1993	10.961538461538462
1994	9.426987060998151
1995	9.457092819614711
1996	9.547738693467336
1997	9.870550161812297
1998	10.223642172523961
1999	10.260336906584993
2000	10.46337817638266
2001	10.256410256410255
2002	9.774436090225564
2003	9.87460815047022
2004	8.892128279883382
2005	8.936825885978427
2006	8.283132530120483
2007	8.61111111111111
2008	8.690176322418136