Year	% of total
1960	97.80069667372447
1961	98.06761786600497
1962	97.78588394977945
1963	98.17276197179285
1964	98.17935452081794
1965	97.84405974512401
1966	97.94741843522331
1967	97.97153511255149
1968	98.02960105280236
1969	98.36713589965976
1970	97.05202042938976
1971	97.50061118541208
1972	97.66585574330988
1973	97.91319063736474
1974	97.31787752955483
1975	97.59877665729873
1976	98.11863229391787
1977	97.83520771172826
1978	97.97517394741185
1979	98.15011385231728
1980	97.71954920167684
1981	97.7849626300064
1982	98.33622213450944
1983	98.26974017922561
1984	98.56753583042274
1985	98.23974289041884
1986	98.49773283692362
1987	98.61613647613271
1988	98.58975352385514
1989	98.71405745225685
1990	98.75385931629654
1991	98.5963775540956
1992	98.5224238064995
1993	98.5938578984512
1994	98.43203745104806
1995	98.35670816246115
1996	98.34624700766321
1997	98.17930251534396
1998	98.17931250044398
1999	98.29858358154586
2000	98.31743193596603
2001	98.01142491354777
2002	97.95086281307238
2003	98.48009119452833
2004	97.69649295313012
2005	97.30173340456619
2006	97.10818342414969
2007	96.41032747337192
2008	95.67384138064766
2009	94.21787838884073
2010	92.98741477761014
2011	91.86294584288675
2012	89.4936027852156
2013	89.50628574215655
2014	87.36025941908295
2015	86.08137957052713