Year	% of total
1970	4.805609255508148
1971	4.535740800559536
1972	4.567896814886012
1973	4.606602607245214
1974	4.3950788196586466
1975	4.408345334219133
1976	4.620700386233682
1977	4.570107855768497
1978	4.680474586909983
1979	4.661544991151027
1980	4.603335718581181
1981	4.470192352683451
1982	4.406415651190276
1983	4.283068422221039
1984	4.111992792350793
1985	4.129182062332895
1986	4.071799341200117
1987	4.168438612030646
1988	4.245246641869431
1989	4.366929023581322
1990	5.494685200327065
1991	5.7152135086864755
1992	5.88235294117647
1993	5.9128110906965095
1994	5.844583470530129
1995	6.2449441837890305
1996	6.655290102389079
1997	6.96657294595439
1998	8.413672217353199
1999	7.51602252864634
2000	7.654822335025381
2001	7.756729810568295
2002	8.383859502404349
2003	8.523560209424083
2004	9.121024734982331
2005	9.206637872243691
2006	9.154113557358054
2007	8.812173518055872
2008	9.144893111638956