Year	% of total
1960	97.46260501331876
1961	96.55707196029778
1962	95.8884741545074
1963	96.13166941880296
1964	95.6220744025622
1965	96.43264970538529
1966	96.93168619997888
1967	97.13984498545518
1968	96.31879720935264
1969	95.14477283341117
1970	91.7009485073816
1971	91.91365747731423
1972	92.34795187060293
1973	93.89807884826237
1974	94.42758378893625
1975	94.6675070259547
1976	95.28017906761346
1977	95.05439522607298
1978	94.8376056497077
1979	94.66434967213956
1980	94.71312458140746
1981	95.18352040235173
1982	96.29833021571622
1983	96.41146206552283
1984	97.05603396362761
1985	96.94166384101665
1986	97.27723130858045
1987	97.3173265290472
1988	97.37603989828192
1989	97.45393143965559
1990	97.49283934084737
1991	97.36453498884937
1992	97.33102756968941
1993	97.32734350693207
1994	97.05688178012514
1995	97.05710658046438
1996	96.86247290961373
1997	96.67790116010927
1998	96.60583500863103
1999	96.5050249641074
2000	96.3310377582522
2001	95.39802812393457
2002	94.74101572642614
2003	95.22628642281464
2004	93.6722386102917
2005	92.2025759692068
2006	92.45042422432883
2007	91.82670807062188
2008	90.88746687350526
2009	89.24835065940538
2010	88.09210065631584
2011	86.79054426856632
2012	84.35789773113764
2013	85.20686249405568
2014	82.9932874050521
2015	80.90616462112315