Year	% of total
1960	58.448563302932236
1961	52.9252383341696
1962	49.980422866092404
1963	49.077523505410674
1964	49.59907478797225
1965	45.83958532260265
1966	41.035606103903525
1967	40.66817789291882
1968	44.3307226771093
1969	34.54954557486985
1970	35.64301109603257
1971	38.72025955299207
1972	35.873246250604744
1973	39.49237429614329
1974	41.834628615110205
1975	46.919817899528965
1976	47.39565044361729
1977	52.6489992172649
1978	52.40599467340766
1979	62.594174062730545
1980	68.61085835608128
1981	70.87176822138495
1982	65.35937292413976
1983	67.61084045339928
1984	68.92053060727758
1985	70.4872040509101
1986	67.34043341817193
1987	68.74942549866716
1988	68.25119203781206
1989	71.33213148709294
1990	77.77337926802053
1991	66.19535581384666
1992	61.29420351328192
1993	63.40827741265998
1994	60.26302703116624
1995	57.53851468428781
1996	56.52157614901513
1997	49.184434988504165
1998	59.76672779428338
1999	69.82140559419136
2000	61.713215553925174
2001	64.85495000142446
2002	59.151160501193324
2003	53.99879952902632
2004	52.83953825260299
2005	49.424853280141846
2006	47.58873403019745
2007	43.02952209111391
2008	43.83866951262896
2009	42.27327548374227
2010	41.336873059957526
2011	39.85503426913286
2012	42.95459798291077
2013	42.35543444504456
2014	40.218283524653245
2015	37.33370489680023
2016	35.51861430269413