Year	% of total
1970	4.567237936141571
1971	4.823146194800487
1972	3.171029012919857
1973	3.769619579952932
1974	4.226989604079775
1975	6.864110499112741
1976	7.0639261803895845
1977	7.046110548567511
1978	8.015343111144208
1979	6.454654937976151
1980	10.424881589986422
1981	8.838737199548838
1982	9.505879558240926
1983	7.6414082616136945
1984	10.160707144407974
1985	6.226469402615729
1986	7.267557476196693
1987	7.209032283759591
1988	8.630305648818833
1989	9.912448606525432
1990	6.390134529147982
1991	5.760869565217392
1992	5.660377358490567
1993	5.399325084364454
1994	5.485714285714286
1995	4.994686503719448
1996	5.01002004008016
1997	4.843304843304843
1998	4.801477377654663
1999	4.529307282415631
2000	4.46584938704028
2001	5.112474437627812
2002	6.163522012578617
2003	6.148055207026349
2004	6.299212598425196
2005	5.615292712066906
2006	5.472103004291846
2007	5.932203389830509
2008	6.832871652816251