Year	% of total
1970	0.19706279245506672
1971	0.40139866900717946
1972	0.38817915957958654
1973	0.37422824070454713
1974	0.45351612013434806
1975	0.3810301010351099
1976	0.45394869514618535
1977	0.38805668243433644
1978	0.3755059514740298
1979	0.27239907480268016
1980	0.37011409486843894
1981	0.44392316794911524
1982	0.38599903666960556
1983	0.4032123536209269
1984	0.5866661319001591
1985	0.5895237241578719
1986	0.6508040062524975
1987	0.43744058902689537
1988	0.7317266509176579
1989	0.6559893724730744
1990	56.53082549634274
1991	55.294117647058826
1992	53.88261028071455
1993	52.67890595728737
1994	51.82737169517885
1995	47.65157984628522
1996	43.89051808406647
1997	37.23346090759978
1998	27.315634218289087
1999	17.57142857142857
2000	2.4496937882764653
2001	2.491408934707904
2002	2.332814930015552
2003	2.214285714285714
2004	2.207977207977208
2005	2.209944751381215
2006	2.4297646165527715
2007	2.4282560706401766
2008	2.4122807017543857