Year	% of total
1960	8.005181347150259
1961	9.382036527395547
1962	10.541894353369763
1963	11.487423252129135
1964	14.04353689077249
1965	15.843583624013219
1966	17.58975284142161
1967	19.326874043855177
1968	18.9149125407649
1969	24.025676295277396
1970	19.376224197679672
1971	21.436516764659146
1972	20.37617554858934
1973	25.120772946859905
1974	29.661683713611332
1975	19.804216867469883
1976	25.34562211981567
1977	27.19242902208202
1978	27.84887263863498
1979	28.847214561500273
1980	29.044647143542967
1981	30.79056865464633
1982	36.84434968017058
1983	42.78717720391808
1984	48.99517684887461
1985	49.7312791114296
1986	50.063979526551506
1987	50.015455950540954
1988	51.70546832701679
1989	55.164895066775685
1990	65.82774305555556
1991	83.70105263157896
1992	81.34411167512691
1993	82.73358790771678
1994	84.79598966026587
1995	78.79064652567976
1996	80.31645659928655
1997	69.97648919346337
1998	74.4639116883117
1999	77.71633018398806
2000	78.03172748267897
2001	73.3826726144298
2002	72.56462267590229
2003	74.77452322738387
2004	75.69418277104488
2005	75.64939162335678
2006	78.77410584958217
2007	77.92495656751777
2008	77.56436988936989
2009	79.26456089385475
2010	77.95818703044681
2011	72.87505512679162
2012	71.99309363683393
2013	71.59063882469461
2014	72.05252664576804
2015	68.04589343004604
2016	72.67860726878222