Year	% of total
1971	20.21834061135371
1972	13.465952563121652
1973	31.026086956521738
1974	27.640156453715775
1975	34.81186907311105
1976	40.338231217077904
1977	36.91962056914628
1978	39.995442114858704
1979	48.41450777202073
1980	51.64856108252335
1981	61.24301675977654
1982	72.46541903986981
1983	72.40502542626383
1984	76.52073399797717
1985	77.80803267528931
1986	64.64451313755795
1987	55.34308211473565
1988	60.396260017809446
1989	65.2593085106383
1990	64.35396759451599
1991	66.95274307441608
1992	72.91902459100731
1993	69.94954591321897
1994	67.06190061028771
1995	45.59212702613298
1996	37.02344871590365
1997	37.570808504377254
1998	28.678285009253546
1999	40.03101977510663
2000	25.639430925911526
2001	15.485843413531835
2002	17.551690187069248
2003	19.109663409337678
2004	18.373340864162664
2005	17.47537584240539
2006	16.45690696737817
2007	17.203598532442076
2008	23.365758754863812
2009	20.189170016552378
2010	24.146671172693477
2011	26.305686635207547
2012	25.311871227364186
2013	20.9565719232434
2014	13.104431920962917
2015	7.173913043478261