Year	% of total
1970	3.848011591295169
1971	3.673414988041131
1972	3.6639353158065253
1973	3.7757998222152604
1974	3.8257665173713167
1975	3.8662962513609465
1976	3.968405411150841
1977	4.034963762473803
1978	4.078577413369715
1979	3.7704309584444657
1980	3.797437556401805
1981	3.7730363323603537
1982	3.6937192336785496
1983	3.6067552216814036
1984	3.5222151416888448
1985	3.4676689354089554
1986	3.3872285281026384
1987	3.3014099731521434
1988	4.13160589357884
1989	4.3086183511967775
1990	5.525136884021902
1991	5.239064089521872
1992	6.363636363636363
1993	6.332138590203106
1994	6.4030131826742
1995	6.481481481481481
1996	7.2727272727272725
1997	7.723855092276145
1998	7.417582417582418
1999	7.013888888888889
2000	7.945597709377237
2001	7.938820101966497
2002	8.2039911308204
2003	8.443465491923643
2004	8.534850640113797
2005	8.266860043509789
2006	8.62190812720848
2007	9.684065934065934
2008	8.37118754055808