Year	% of total
1970	7.6710072774669165
1971	7.366841578922193
1972	7.394867202537854
1973	7.282116947941953
1974	7.193645924320026
1975	7.821926279406492
1976	8.193677430262811
1977	8.279748233649837
1978	8.459332620133289
1979	8.645641374948202
1980	8.764034797891796
1981	8.804557400399952
1982	8.928337112190604
1983	8.758842544806072
1984	8.457784656960389
1985	8.355656370477336
1986	8.359818130832046
1987	8.333913560033078
1988	8.634223467773989
1989	9.171496757870818
1990	5.802047781569966
1991	5.366726296958855
1992	4.564315352697095
1993	4.739336492890995
1994	5.2356020942408374
1995	4.864864864864865
1996	3.864734299516908
1997	3.5377358490566038
1998	3.34075723830735
1999	2.9017857142857144
2000	2.55863539445629
2001	2.5316455696202533
2002	2.6052104208416833
2003	2.5540275049115913
2004	2.631578947368421
2005	2.5134649910233393
2006	2.717391304347826
2007	2.5437201907790143
2008	2.671118530884808