Year	% of total
1970	31.449219613104656
1971	30.27002886124746
1972	29.002496642443294
1973	27.129607209027174
1974	24.397106480023258
1975	23.316282209912277
1976	22.878398038421626
1977	23.521981965087765
1978	19.347954911759594
1979	20.22214667449856
1980	22.934121970337255
1981	21.31040519373551
1982	21.050060120218113
1983	20.378311735802413
1984	21.20004551444289
1985	22.482466298411495
1986	22.81530747830666
1987	22.64828548013621
1988	22.375758312931207
1989	22.510197496167752
1990	5.617977528089887
1991	4.444444444444445
1992	4.395604395604396
1993	4.3478260869565215
1994	4.301075268817205
1995	4.2105263157894735
1996	3.8461538461538463
1997	3.5398230088495577
1998	3.278688524590164
1999	3.0303030303030303
2000	2.8368794326241136
2001	1.9607843137254901
2002	2.054794520547945
2003	1.9867549668874174
2004	1.3157894736842104
2005	1.3245033112582782
2006	1.257861635220126
2007	1.2345679012345678
2008	1.2195121951219512