Year	% of total
1960	60.051708077486076
1961	61.15874154926918
1962	61.00353982300884
1963	63.65468125759946
1964	60.486669031133864
1965	60.23006558759798
1966	60.13971180904167
1967	60.88404402008483
1968	59.08596694694115
1969	59.10126567178422
1970	61.94858468278854
1971	62.53626881038302
1972	61.26692130810011
1973	62.462404750694255
1974	63.88392605269592
1975	60.981329984672485
1976	58.581202075393726
1977	57.30521814130669
1978	56.268075051139164
1979	55.30679452191152
1980	54.48453309726899
1981	53.04486496166737
1982	50.33946251768033
1983	47.46164199192463
1984	45.26929804154712
1985	44.259873851019094
1986	46.063245185996614
1987	46.836691320241435
1988	46.27835358254199
1989	44.64127406281661
1990	49.08610922886047
1991	46.59833167849273
1992	46.42284272300469
1993	47.881469906312105
1994	46.00003395469668
1995	45.74327563959956
1996	44.760740348907504
1997	44.96678578145571
1998	46.08535171337004
1999	45.99339600920951
2000	44.89262446601942
2001	45.70259340355861
2002	42.64081698289151
2003	44.89950216370837
2004	47.16147640763146
2005	45.91534465516301
2006	48.692950819672134
2007	46.394793369624196
2008	46.902542893493276
2009	49.11231125192012
2010	46.89315982281367
2011	44.70001497115314
2012	44.224633914537414
2013	43.512957490788175
2014	45.08968211024687
2015	48.197294559770945
2016	45.876136462723444