Year	% of total
1960	99.87404694919272
1961	99.16221057747595
1962	99.2578421211771
1963	99.66478241816876
1964	99.40883472172415
1965	98.87262589469896
1966	99.62772210752927
1967	99.23595844786807
1971	99.13182259433617
1972	99.16203772761637
1973	98.22457031868906
1974	98.01599456915532
1975	97.41028202082876
1976	97.5290796360073
1977	97.67494495533495
1978	96.21508856720922
1979	96.1169683972957
1980	97.16715919587962
1981	92.80376319560972
1982	94.28114564696996
1983	92.57050096517513
1984	92.22414619485116
1985	94.91503626476566
1986	94.75662709629928
1987	93.04936063558027
1988	91.83152448323978
1989	88.61327835883644
1990	89.59051862065294
1991	94.08441927366891
1992	90.72488797820483
1993	91.7570149714862
1994	94.63847162579766
1995	92.36304094449997
1996	98.52626245851337
1997	94.36666381642671
1998	92.6766256004631
1999	90.89289457519497
2000	88.28005040249923
2001	88.27070130072721
2002	87.98990846508892
2003	89.67967719201721
2004	85.4747882362454
2005	82.18730305258181
2006	86.63662222239762
2007	82.03661354990057
2008	80.1313683361241
2009	79.57580425754406
2010	78.27422570908509
2011	74.82227821003619
2012	70.8623706607139
2013	70.2593871097906
2014	67.70455812388114
2015	64.92708946756662