Year	% of total
1960	16.661312086358674
1961	19.49014900077678
1962	19.776347001016607
1963	20.584589286879364
1964	22.48639543923296
1965	22.18133558544972
1966	25.141460905349795
1967	23.86338310675284
1968	24.699703894072293
1969	24.18686224489796
1970	25.215167461761666
1971	31.305316218275603
1972	31.637855259302665
1973	35.54452715743038
1974	32.37346869051686
1975	37.056829282307646
1976	38.92441488681417
1977	39.42462600690449
1978	37.817638266068755
1979	39.260571811694845
1980	36.26524513367257
1981	34.41387559808612
1982	35.30543341708543
1983	36.79940131553035
1984	40.40360332008969
1985	36.1454071472537
1986	37.47698282500251
1987	36.94696844539897
1988	36.86355022109918
1989	35.9002863399023
1990	41.09728374709077
1991	42.106571930852624
1992	18.476778997613362
1993	36.19722534955511
1994	45.39129792440859
1995	48.92469129468103
1996	49.12539232948021
1997	48.34839549768263
1998	60.62780712345306
1999	61.07735409475996
2000	39.742432472654215
2001	44.373130599461
2002	38.29972180244539
2003	37.55687762490949
2004	35.82993484657419
2005	33.05117344672209
2006	37.90056975115084
2007	37.999701531614086
2008	34.2139690500948
2009	33.13564997254926
2010	34.55837281213536
2011	28.156474908919964
2012	27.066379600935143
2013	25.869075021312877
2014	24.786077515264136
2015	26.726415343915345
2016	30.110310378872025