Year	% of total
1970	18.77636085412856
1971	18.181294187787664
1972	17.955300627305785
1973	17.882459885027345
1974	17.66618307905769
1975	17.31835724364434
1976	17.29979557437034
1977	17.05524762480913
1978	16.563891588739924
1979	16.324755727048665
1980	16.209896465219234
1981	16.14784617741783
1982	16.07857269047869
1983	15.916541498590759
1984	15.734033107305862
1985	15.568624206735763
1986	15.46326319167578
1987	15.214048474823944
1988	21.60146256816107
1989	26.020406292815444
1990	12.40694789081886
1991	12.686567164179104
1992	10.10989010989011
1993	11.704834605597965
1994	15.789473684210526
1995	17.374517374517374
1996	17.647058823529413
1997	17.21311475409836
1998	16.666666666666664
1999	17.040358744394617
2000	17.061611374407583
2001	17.370892018779344
2002	17.050691244239633
2003	16.19047619047619
2004	17.15686274509804
2005	17.475728155339805
2006	15.121951219512194
2007	15.609756097560975
2008	14.492753623188406