Year	% of total
1960	99.1304347826087
1961	99.14639743001376
1962	98.8466567052671
1963	98.80675586751481
1964	98.54748603351955
1965	97.91897891231964
1966	97.53887380557809
1967	96.87825182101977
1968	95.47540770157221
1969	92.42347025447627
1970	88.88313779618127
1971	86.19030820050672
1972	76.75585808839675
1973	75.78835863867235
1974	74.84771710419923
1975	77.88687498545801
1976	71.89924628685435
1977	77.92329483547614
1978	75.4603550295858
1979	69.41383481799186
1980	68.09548521017125
1981	68.4512096307443
1982	69.19517025976994
1983	67.8609062170706
1984	60.87983049137322
1985	57.70747429641501
1986	58.191400930298364
1987	58.96930011055361
1988	59.97352458192299
1989	55.39079796833429
1990	54.18060808844923
1991	56.39019759510583
1992	56.077651255316226
1993	58.780808412750574
1994	59.720269030877404
1995	56.498200745405484
1996	51.10131375442214
1997	54.91515034197961
1998	53.72207241910631
1999	58.2528795887758
2000	55.70443409352126
2001	58.13279292971938
2002	53.79057511647445
2003	53.24006116207951
2004	52.84271510216863
2005	54.03450483656059
2006	49.82457834427707
2007	53.05618687818902
2008	53.7561907035026
2009	53.57940995605418
2010	54.59486465209229
2011	51.504261544332785
2012	56.64807748752568
2013	55.967694994179276
2014	54.25808108185216
2015	57.88159825710698