Year	% of total
1970	0.9068720553226997
1971	1.4070857691907108
1972	1.1124461933573995
1973	0.8028632204877185
1974	1.4644722039171565
1975	1.5061677209517477
1976	1.5587456607095902
1977	1.034900410497981
1978	0.8825836709203154
1979	1.0175545233458587
1980	0.9010282732695796
1981	1.0408650064124376
1982	1.0513307380077008
1983	0.5833583664555373
1984	1.0120156978137653
1985	1.220613338256317
1986	1.0540448615349742
1987	0.8055805319443334
1988	1.0126556233465478
1989	1.5137938461254683
1990	4.147880973850315
1991	4.129263913824058
1992	4.052863436123348
1993	3.968938740293356
1994	3.811101905550953
1995	3.6585365853658534
1996	3.739061256961018
1997	3.8981702466189336
1998	3.975058456742011
1999	3.9215686274509802
2000	3.938730853391685
2001	4.0358744394618835
2002	4.175988068605518
2003	4.054054054054054
2004	3.8280725319006046
2005	3.8978494623655915
2006	3.749191984486102
2007	3.522867737948084
2008	3.45679012345679