Year	% of total
1970	9.613178546541686
1971	9.535720570833742
1972	9.306946517412936
1973	8.531094874557008
1974	9.264863931225076
1975	9.892450794886653
1976	11.954449015492441
1977	11.470009316566433
1978	10.788830954255618
1979	10.804182703565509
1980	10.350175298828734
1981	10.139656119315747
1982	10.316504025012026
1983	9.636151794071194
1984	10.378360853328616
1985	9.713859154662773
1986	8.794519267093879
1987	8.201150971177945
1988	8.858158562453378
1989	9.447514187821822
1990	8.008898776418242
1991	9.036860879904875
1992	9.080590238365494
1993	9.022556390977442
1994	9.233997901364113
1995	9.184726522187821
1996	8.563273073263558
1997	8.125
1998	8.993157380254155
1999	8.417200365965233
2000	8.363309352517986
2001	8.267370272647318
2002	8.579088471849866
2003	7.990115321252059
2004	7.722616233254531
2005	8.06845965770171
2006	8.411214953271028
2007	8.094848732624694
2008	8.527131782945736