Year	% of total
1971	83.75470161696848
1972	88.67135558821471
1973	89.43855637610852
1974	91.60378805841086
1975	91.5778805346171
1976	92.09178856641454
1977	92.54346018294855
1978	91.14424859619086
1979	91.95891902125042
1980	92.48600947051227
1981	91.96691680674041
1982	92.79566569574393
1983	93.21882654128768
1984	92.86638051173422
1985	92.09683914870767
1986	90.24924800126652
1987	91.27973599697046
1988	92.6242282981386
1989	92.40124050324346
1990	92.76863491322631
1991	92.91952708670219
1992	92.39281518375722
1993	93.2886465377655
1994	93.33335897031621
1995	92.12774989931096
1996	91.24238699798818
1997	90.58061834782552
1998	90.58921889180353
1999	87.53689695144541
2000	87.24398842108279
2001	81.54321964761894
2002	82.76424692843773
2003	83.88231839029037
2004	82.7963649784619
2005	83.729372036533
2006	83.18011527721141
2007	84.02055950056948
2008	79.80616195928451
2009	83.8812239740325
2010	78.19542603418355
2011	80.55051461475824
2012	75.15815454992907
2013	68.46344572541219
2014	63.22498395837813
2015	61.848493600984774