Year	% of total
1970	1.3496968127902622
1971	1.342392442111375
1972	1.3898018446016003
1973	1.4467965492451471
1974	1.4523275193368943
1975	1.6127177193477646
1976	1.7594191024035435
1977	1.7979028824107437
1978	1.8872745226244645
1979	2.0694615295108116
1980	2.1027969440378644
1981	2.049779860263946
1982	2.265362920933215
1983	2.41543376965978
1984	2.514045263625312
1985	2.566870010962373
1986	2.6728734912276635
1987	2.795806372665119
1988	2.8280235342409523
1989	2.8905464952860567
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0
1998	0
1999	0
2000	0
2001	0
2002	0
2003	0
2004	0
2005	0
2006	0
2007	20
2008	20