Year	% of total
1960	29.116390616802818
1961	31.233775105888782
1962	36.4230323013983
1963	34.760925129356025
1964	42.846569883290634
1965	44.68392286274106
1966	51.13459451809218
1967	55.04789353225396
1968	58.595961502170226
1969	57.59273277819833
1970	61.60190673315144
1971	65.39097230137924
1972	67.17742547219905
1973	68.80738275626048
1974	71.15779664965373
1975	69.31664479660846
1976	71.51304604922758
1977	68.60826867573748
1978	72.85048010973937
1979	70.74079406788812
1980	68.72185837085551
1981	63.55080667987545
1982	59.08249187659411
1983	56.202119281162744
1984	56.247350474610634
1985	54.02081017548335
1986	52.39791301669202
1987	54.16786736595394
1988	59.11712143265103
1989	56.139385899634384
1990	55.5831383127151
1991	55.75833490841997
1992	55.893042412250516
1993	57.04521113199762
1994	58.83315153637398
1995	57.47730609360712
1996	60.49832855280314
1997	57.40261413458831
1998	59.03953009132776
1999	57.11512917250548
2000	54.8455978316457
2001	56.676228501645234
2002	53.725214068745
2003	54.475652105692596
2004	53.43246066277268
2005	51.89772753209701
2006	53.105945052372874
2007	51.48770722905154
2008	53.84775018509378
2009	56.305395318098014
2010	56.90996120768528
2011	53.146108965014584
2012	49.4276246889739
2013	52.97667174629325
2014	53.55165297144754
2015	53.292264320274704
2016	56.7722199732826