Year	% of total
1970	2.5548084191606857
1971	2.6677425737642655
1972	2.2348123662306776
1973	3.1398688106143964
1974	2.7834026516138373
1975	2.610645139688187
1976	2.285312495530287
1977	2.52009666833398
1978	3.0855640206144375
1979	2.632206888515811
1980	2.599253761057961
1981	3.616487607318227
1982	3.042417868663195
1983	3.476878741625885
1984	3.586659534764378
1985	2.840061646237178
1986	3.2350941184463125
1987	3.8129485996229775
1988	3.886504133776118
1989	3.824609530405105
1990	2.527909662517644
1991	2.6230359693546292
1992	2.7303754266211606
1993	2.921437031188314
1994	3.032300593276203
1995	3.2223983095615423
1996	3.615318662474993
1997	3.8400231850456454
1998	3.835690968443961
1999	3.2471835652750163
2000	3.1015609162781272
2001	2.923119215614405
2002	3.338554924613276
2003	5.92401802962009
2004	4.4126207940388875
2005	6.055802155992391
2006	4.592269477765662
2007	4.920144255538382
2008	6.1674718196457325