Year	% of total
1960	93.77638048935982
1961	93.60324055808007
1962	94.42113367379139
1963	94.60904531539282
1964	95.20367033281427
1965	95.14102392216938
1966	95.26393589017623
1967	96.50803223565785
1968	96.6425595245175
1969	97.01007706179729
1970	97.00480674457198
1971	96.51399786561029
1972	96.5739067579185
1973	97.34559990980391
1974	96.1724417757311
1975	95.47404891000811
1976	94.9935627986153
1977	95.52269975552451
1978	93.39450471792371
1979	92.610890913916
1980	91.32407255619313
1981	90.7445214476561
1982	88.51455277981916
1983	87.43145522646029
1984	87.10336967688794
1985	84.9682291429023
1986	84.56660030791178
1987	83.47244169794277
1988	84.73903951432817
1989	84.91936201046106
1990	84.55205339107097
1991	83.8847678901191
1992	83.95401953761076
1993	82.42967512253773
1994	82.68251328594704
1995	81.47549791084448
1996	81.2193281130974
1997	80.35858715038619
1998	79.39872965637733
1999	80.61843811737995
2000	80.67376563425594
2001	80.601638342528
2002	81.83018976969308
2003	84.31138173902211
2004	82.70647334241079
2005	81.61186176445815
2006	81.45311669863526
2007	83.48271492333387
2008	83.21545458243469
2009	81.22805604231299
2010	80.91095442176412
2011	89.76594207466343
2012	94.62155285384954
2013	94.63330153072364
2014	94.40746890159542
2015	93.02645510746291