Year	% of total
1970	6.608359269968088
1971	7.122115186660224
1972	6.849005586073134
1973	6.434863505324946
1974	8.19212049297151
1975	7.072701303995256
1976	8.464451601159114
1977	7.871800397778064
1978	8.280143614089777
1979	7.872528054961476
1980	8.716802866622636
1981	8.146158968377994
1982	8.631075957622294
1983	9.039614003951867
1984	8.879476632525098
1985	8.294653377275798
1986	8.369137845771352
1987	8.411660762190015
1988	8.976232014337207
1989	11.107947463982542
1990	1.3349514563106795
1991	1.3729977116704806
1992	1.4038876889848813
1993	1.443298969072165
1994	1.5952143569292123
1995	1.8888888888888888
1996	2.1437578814627996
1997	2.4853801169590644
1998	2.9565217391304346
1999	3.5940803382663846
2000	4.683195592286501
2001	5.10752688172043
2002	5.46875
2003	5.5696202531645564
2004	5.9259259259259265
2005	5.952380952380952
2006	6.279069767441861
2007	6.208425720620843
2008	6.315789473684211