Year	% of total
1970	5.335748213908262
1971	5.152870123859876
1972	4.941055375586843
1973	4.820707249181187
1974	4.88122694260676
1975	4.915544115100675
1976	4.89049625817748
1977	4.634246110993953
1978	4.267955681380819
1979	4.214330048091817
1980	4.111468823663071
1981	4.10061573881459
1982	4.112161313451619
1983	4.143976276145818
1984	4.299797582633276
1985	4.361215571074661
1986	4.281924312369764
1987	4.312573561434721
1988	4.2535695358461005
1989	7.0903193992102445
1990	5.655296229802514
1991	5.431878895814782
1992	5.30035335689046
1993	5.225863596102745
1994	4.875962360992301
1995	4.453781512605042
1996	4.401993355481728
1997	4.25531914893617
1998	4.093097913322633
1999	4.0669856459330145
2000	4.0669856459330145
2001	4.0551500405515
2002	3.9808917197452227
2003	3.735408560311284
2004	3.62095531587057
2005	3.6565977742448332
2006	3.5455278001611608
2007	3.5044824775876124
2008	3.5532994923857872