Year	% of total
1960	21.826280623608017
1961	18.951669719599828
1962	22.59607718067294
1963	23.595686463866087
1964	23.43212706729982
1965	24.55072033268974
1966	25.971786833855802
1967	24.947745595700212
1968	22.88980459922903
1969	14.979134636503405
1970	6.428498310983724
1971	6.960120391271632
1972	4.611219223284542
1973	6.403462944995895
1974	6.388153659060018
1975	9.472682794237564
1976	9.136212624584719
1977	8.042704626334519
1978	8.385384134915677
1979	7.770022750935102
1980	12.844320643763544
1981	13.388738375924433
1982	14.732997042963996
1983	13.014464398015512
1984	21.75661098944203
1985	22.347568352286476
1986	18.798758998765024
1987	21.9117821899893
1988	17.699286923226325
1989	19.07041859162817
1990	29.798866139604023
1991	26.897526569451312
1992	30.668830378561818
1993	31.112561462152254
1994	30.649885746204237
1995	29.001619098905046
1996	33.71581925963835
1997	31.865485698761987
1998	18.40661560848587
1999	30.00870174558228
2000	17.357944819216904
2001	20.280698075075374
2002	19.542716134091354
2003	18.69965530607985
2004	18.048615806037997
2005	15.823254065040649
2006	15.784919252952486
2007	15.033561240065266
2008	16.003628771408877
2009	16.37410454003904
2010	17.69823979469468
2011	16.98790450817966
2012	16.461760041088855
2013	14.264591257263604
2014	12.747137026833997
2015	19.218056393121994
2016	18.437235645884684