Year	% of total
1970	0.2254259644398495
1971	0.36059769280762566
1972	0.3216113121656994
1973	0.4028183203976629
1974	0.35565470297419177
1975	0.3436861100904947
1976	0.35359700067348765
1977	0.47017654641930884
1978	0.4090121877276794
1979	0.375953923092085
1980	0.5115662330020637
1981	0.6441110897745972
1982	0.5982603322711209
1983	0.5797843865012235
1984	0.7840601844628468
1985	0.7387378273203473
1986	0.6969564302792115
1987	0.5536024543972901
1988	0.595655850545693
1989	0.6438006688012082
1990	1.7964071856287425
1991	1.9455252918287937
1992	1.9047619047619049
1993	1.858736059479554
1994	1.9855595667870036
1995	1.9400352733686066
1996	2.010968921389397
1997	1.9400352733686066
1998	1.8272425249169437
1999	1.7322834645669292
2000	1.8181818181818181
2001	1.8242122719734661
2002	1.5942028985507246
2003	1.8181818181818181
2004	1.6107382550335572
2005	1.5
2006	1.694915254237288
2007	1.8300653594771243
2008	1.8252933507170794