Year	% of total
1970	3.704218029268622
1971	3.6084239602281616
1972	3.4575194283749187
1973	3.519233964375158
1974	3.2678730212017895
1975	3.3926287302680143
1976	3.3328681646276794
1977	3.124196335560895
1978	9.6908287718176
1979	9.059561973310357
1980	10.77333056084739
1981	11.044543269068322
1982	11.109294199120963
1983	10.774899304015138
1984	10.559422877214027
1985	10.85452876080156
1986	9.716749948211078
1987	10.553784244068906
1988	10.677042279624068
1989	10.159319640720305
1990	6.733167082294264
1991	7.641196013289036
1992	7.2992700729927
1993	7.723577235772358
1994	6.405693950177936
1995	6.529209621993128
1996	6.050955414012739
1997	6.270627062706271
1998	6.36042402826855
1999	7.758620689655173
2000	6.976744186046512
2001	7.194244604316546
2002	6.521739130434782
2003	6.785714285714286
2004	6.666666666666667
2005	7.317073170731707
2006	6.289308176100629
2007	6.7340067340067336
2008	6.993006993006993