Year	% of total
1970	32.58465295478714
1971	32.747952605503485
1972	37.15608067266216
1973	36.99528523339093
1974	34.73654493190707
1975	36.38571229128274
1976	32.377413526274026
1977	33.68597652436846
1978	35.18808067092652
1979	27.156273149291323
1980	25.92927348408645
1981	26.835594236386623
1982	37.081129916021695
1983	35.900246824874095
1984	36.75571996154648
1985	36.32336452293095
1986	38.842476050752786
1987	39.66367193857171
1988	36.67840794345339
1989	27.02494428131744
1990	56.60109030575966
1991	58.26357330782109
1992	58.58323494687131
1993	60.37511870845205
1994	57.4678981752647
1995	58.62894450489663
1996	58.52202552490737
1997	59.35622317596566
1998	65.7653528872594
1999	69.61529037000736
2000	69.5796178343949
2001	68.77409406322282
2002	68.4511952191235
2003	68.93846531012503
2004	66.51754179420767
2005	68.69364161849711
2006	69.93785603314345
2007	72.47230732971954
2008	71.01346562721474