Year	% of total
1960	94.02150650561848
1961	93.95176934840252
1962	94.14510041765017
1963	94.50935993934391
1964	95.00374686109103
1965	95.02813063001868
1966	94.34535818257164
1967	94.7014071935444
1968	94.93965044798296
1969	95.17184392898996
1970	94.33540762970964
1971	94.18444638219202
1972	93.52201812476535
1973	94.32892069368542
1974	94.11210288178418
1975	93.22477450131943
1976	93.88719320189762
1977	92.56546160300681
1978	92.42799043801136
1979	92.04647759070674
1980	91.23984580580539
1981	89.07712431454709
1982	88.01324583918964
1983	86.52584899564164
1984	84.33698768744391
1985	82.5424083658352
1986	81.80502828327865
1987	81.48562737514942
1988	80.53126380185142
1989	80.17596519611061
1990	79.56676722767658
1991	79.33162428792248
1992	78.54812658166023
1993	77.85387055600297
1994	78.01743193205056
1995	78.06609718217663
1996	77.74822462820381
1997	77.37886920632009
1998	77.80392056047717
1999	77.3487095763229
2000	76.83885377178625
2001	76.77614419180378
2002	76.60436832292616
2003	76.4432863318021
2004	76.3220432715407
2005	76.11145752881069
2006	75.5805138031328
2007	75.21275897011013
2008	74.3904873323779
2009	73.4728205894215
2010	72.7811999660712
2011	72.33455766169584
2012	71.69580201759442
2013	70.84715101678735
2014	69.41660493849797
2015	69.95485442857749