Year	% of total
1965	99.32897915361903
1966	99.1569007672203
1967	99.34347477982386
1968	99.32345115925504
1969	99.32475655696922
1970	99.39485627836612
1971	99.35974389755903
1972	99.3261042700484
1973	99.4275349997166
1974	99.57334737951014
1975	99.20379054318093
1976	99.25170068027211
1977	99.36330228185625
1978	99.45973456524293
1979	99.40454341531057
1980	99.53090970011728
1981	99.30864197530865
1982	99.3582240161453
1983	89.81000387747189
1984	84.78880736037713
1985	75.01865950141811
1986	72.82639680729761
1987	62.3516756865777
1988	53.27882872096603
1989	52.48301274466719
1990	50.96708397805598
1991	53.38250508961052
1992	55.142812056178
1993	57.34771380829409
1994	57.33253766970014
1995	57.986948086307244
1996	58.740381875178116
1997	59.660423199706194
1998	61.77467061037913
1999	61.944914358215264
2000	58.85879912477622
2001	60.34875738020047
2002	60.67428160522167
2003	66.66569043783863
2004	61.798386139788775
2005	55.87873363910953
2006	57.92966898128782
2007	58.193193193193196
2008	56.80449718925672
2009	48.65211095020609
2010	49.33772176286425
2011	48.5604819678503
2012	46.4212501804533
2013	39.621707268766095
2014	35.4858464888405
2015	36.5598839891899