Year	% of total
1960	0.2555118221186815
1961	0.510793756227167
1962	0.5279505691706846
1963	0.44840790004030634
1964	0.4649601342845153
1965	0.4437630490219493
1966	0.4917020888570907
1967	0.6466684723726978
1968	0.5732025837126011
1969	0.6517844664388174
1970	0.7138036897282602
1971	0.8190412448757635
1972	0.9970752982762762
1973	1.1850494464721115
1974	1.4626958735720066
1975	1.4826670080983324
1976	1.6204533958706948
1977	1.77485482403974
1978	1.7991809137351187
1979	1.8596744281887492
1980	1.86350151334518
1981	1.6815384459916933
1982	1.45031454421835
1983	1.407161853309371
1984	1.3359464974844928
1985	1.263136696228118
1986	1.274695903851914
1987	1.2047932850199057
1988	1.1535681841747283
1989	1.1975974970120964
1990	1.3492932141936909
1991	1.3379781859881243
1992	1.251509440984542
1993	1.3526200572719054
1994	1.505196099714172
1995	1.376757983318584
1996	1.4521409973636814
1997	1.4125799945663466
1998	1.5637495204385974
1999	1.7342911850628733
2000	1.789588198882207
2001	1.9057898348337705
2002	1.4189135920469076
2003	1.377544989010491
2004	1.3975442371183735
2005	1.461161292429096
2006	1.6144261813364924
2007	1.9380257748407674
2008	2.081956105689916
2009	2.228306453180836
2010	2.358150915463776
2011	2.6534247191011233
2012	2.914302611607213
2013	3.2243109066609774
2014	3.5763750765542794
2015	3.732790488310277
2016	4.107179292278317