Year	% of total
1964	84.00447427293065
1965	82.30337078651685
1966	81.04712041884817
1967	76.81713848508033
1968	72.81475541299119
1969	67.58147512864494
1970	64.68871595330738
1971	57.350096711798834
1972	57.529305680793506
1973	49.04153354632588
1974	47.29493891797557
1975	45.55256064690027
1976	44.62659380692167
1977	42.507345739471106
1978	40.40084388185654
1979	37.23296032553408
1980	38.3177570093458
1981	33.66013071895425
1982	38.4375
1983	30.94170403587444
1984	40.05201560468141
1985	40.21304926764314
1986	42.38578680203046
1987	37.99185888738128
1988	43.99066511085181
1989	33.66197183098591
1990	30.379890510948904
1991	29.157743055555557
1992	30.622666666666664
1993	35.0693253968254
1994	39.24032710280374
1995	15.494366197183096
1996	23.960511363636364
1997	21.23
1998	21.29225806451613
1999	15.834772727272728
2000	16.00513812154696
2001	16.43136612021858
2002	15.852135416666666
2003	15.440000000000001
2004	11.29644549763033
2005	13.771266375545851
2006	6.055596330275229
2007	14.816161616161615
2008	14.466146788990827
2009	16.479230769230767
2010	14.445757575757575
2011	8.748071895424836
2012	8.665796019900498
2013	10.810731132075471
2014	10.08425
2015	9.547218934911243
2016	15.28463327370304