Year	% of total
1970	3.633307087845013
1971	4.4295133883958355
1972	3.934135118284877
1973	4.309707411791439
1974	4.1674407727034435
1975	3.840477676864462
1976	3.470037897636292
1977	4.005524659536241
1978	3.7691484381706863
1979	3.8425014908132447
1980	3.8344267816740767
1981	3.965490544542428
1982	3.854508101230028
1983	3.848233302391081
1984	4.289044878286546
1985	4.178396392323952
1986	4.4295696962555375
1987	4.892395542918164
1988	5.847898783025799
1989	5.6156918677936085
1990	1.9988577955454025
1991	2.2222222222222223
1992	2.21316249271986
1993	2.178649237472767
1994	2.1232522009321597
1995	2.3890784982935154
1996	2.7160493827160495
1997	3.024390243902439
1998	3.2723772858517806
1999	3.561253561253561
2000	3.942307692307692
2001	3.705397987191217
2002	3.7700282752120637
2003	3.4847816497573887
2004	3.62453531598513
2005	3.451367099955177
2006	3.633141338059371
2007	3.6523929471032743
2008	3.929944468175993