Year	% of total
1960	96.02612608686673
1961	96.20098474203424
1962	96.38701005026452
1963	96.43044142352139
1964	96.56313379476443
1965	96.92506310108831
1966	96.67282032327556
1967	96.51037089654052
1968	96.13213329639139
1969	96.30037291677783
1970	96.72091820178781
1971	67.37176673971462
1972	68.04089220555336
1973	68.91978979835291
1974	69.06654592443003
1975	70.52788868942011
1976	71.2386823195965
1977	72.59808157993587
1978	74.3201673898012
1979	74.32428350082996
1980	74.01266432940685
1981	72.91328295755162
1982	73.25108085792493
1983	73.7370664539304
1984	74.09202379228674
1985	73.8400588003076
1986	74.55205165634986
1987	75.11264413359294
1988	75.69902925757393
1989	75.57895999803388
1990	83.1428545844349
1991	82.71497327884131
1992	82.36297709293906
1993	82.25332308793733
1994	81.7236510658656
1995	82.1389788849112
1996	82.28884487888176
1997	82.1537454464677
1998	82.02306104622296
1999	81.89191072761686
2000	82.23099479174579
2001	82.5342710914742
2002	82.57737774349255
2003	83.59668447265207
2004	84.22106320272081
2005	84.75466218948989
2006	85.32363796274275
2007	85.67882139635726
2008	85.58686813325859
2009	85.29799263748514
2010	85.66001193674295
2011	86.4875007442724
2012	86.04695793746276
2013	86.08624935039828
2014	86.18233309317407
2015	78.99368880656947