Year	% of total
1970	4.762569370601042
1971	4.65113343235549
1972	4.6363118249825614
1973	4.978302723435234
1974	4.5220660298799915
1975	4.4263080077953205
1976	5.468003011479296
1977	5.750182000946652
1978	5.356868024248635
1979	5.75527299282222
1980	8.090897800043749
1981	10.515685204975847
1982	11.498468784814769
1983	10.660898704048755
1984	10.86632091419298
1985	10.958402321443945
1986	11.915345100188125
1987	12.140274397510002
1988	13.173253907104282
1989	13.241026931578709
1990	11.294765840220386
1991	11.716621253405995
1992	9.657320872274143
1993	10.41879468845761
1994	10.422812192723697
1995	10.43956043956044
1996	10.673665791776028
1997	10.303514376996805
1998	9.44755804643715
1999	9.653092006033184
2000	10.028653295128938
2001	10.332625619249823
2002	11.11111111111111
2003	9.271137026239067
2004	8.299595141700406
2005	8.842794759825328
2006	9.509746012994684
2007	19.862227324913892
2008	29.118329466357306