Year	% of total
1960	0
1961	0
1962	0
1963	0
1964	0
1965	0
1966	0
1967	0
1968	0
1969	0
1970	0
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0.058466710516699556
1984	0.42537851478010097
1985	2.1425955316811134
1986	3.6170080308784165
1987	4.638592080452546
1988	5.755922278413628
1989	7.411304870715574
1990	7.991637864823349
1991	7.5117089112067585
1992	8.689908787931943
1993	9.462826783606005
1994	9.923358126285803
1995	12.117256341789053
1996	11.6713656207367
1997	14.133948524795983
1998	16.376893203883498
1999	18.058172401685393
2000	19.33332005312085
2001	19.693526462395543
2002	19.63251204149685
2003	17.988940006740815
2004	19.692518092410467
2005	20.04558583648299
2006	17.846780621886275
2007	17.421683520599252
2008	18.613024740622507
2009	18.629799540613906
2010	21.02169779991698
2011	19.760440937572522
2012	20.88299398063334
2013	18.995390195097546
2014	17.95558445190157
2015	19.44819642857143
2016	18.635573770491803