Year	% of total
1970	0.14993192819869428
1971	0.13836074950418056
1972	0.14094821731647103
1973	0.15840675489021294
1974	0.2230343491150122
1975	0.29520648859030646
1976	0.3207597112015115
1977	0.4009601666769582
1978	0.4760628580017637
1979	0.623461757005578
1980	0.8932135947267035
1981	1.0058663544431534
1982	1.228600276324833
1983	1.0003264462071684
1984	1.0693670208005153
1985	1.2657987311302545
1986	1.0261250013440348
1987	1.194183553220544
1988	1.0060725004076831
1989	0.8541827573008177
1990	3.2388663967611335
1991	0.7547169811320755
1992	0.6944444444444444
1993	1.5923566878980893
1994	1.7699115044247788
1995	2.197802197802198
1996	2.710027100271003
1997	2.949061662198391
1998	2.9177718832891246
1999	3.1413612565445024
2000	3.6175710594315245
2001	2.261306532663317
2002	2.8846153846153846
2003	3.009259259259259
2004	2.696629213483146
2005	2.391304347826087
2006	2.5974025974025974
2007	2.795698924731183
2008	2.9914529914529915