Year	% of total
1970	3.7728671577242836
1971	3.6861717440524147
1972	3.563423923091144
1973	3.7608297197013725
1974	3.845364439832541
1975	3.954265346897497
1976	4.208121307405286
1977	4.316009362980433
1978	4.400399966784764
1979	4.157777423614589
1980	4.184065085605237
1981	4.132243539610962
1982	4.038639239316988
1983	4.281039373801581
1984	4.151895943993922
1985	3.9090217366689424
1986	3.6230950393331343
1987	3.609615390473869
1988	3.4041728533196243
1989	3.579158429383167
1990	5.3097345132743365
1991	5.357142857142857
1992	5.88235294117647
1993	5.785123966942149
1994	5.932203389830509
1995	5.982905982905983
1996	5.785123966942149
1997	6.25
1998	6.086956521739131
1999	5.405405405405405
2000	5.454545454545454
2001	5.785123966942149
2002	5.785123966942149
2003	5.6000000000000005
2004	6.557377049180328
2005	6.504065040650407
2006	6.349206349206349
2007	7.317073170731707
2008	7.03125