Year	% of total
1971	33.624454148471614
1972	38.94414690130069
1973	58.53913043478261
1974	56.42112125162973
1975	68.920159070052
1976	72.33157748821736
1977	65.92611083374938
1978	67.73017319963537
1979	67.21243523316062
1980	71.12635791881074
1981	82.12290502793296
1982	90.69161920260375
1983	92.80586299730781
1984	94.71174685739055
1985	93.38325391422737
1986	91.71818650180319
1987	89.68878890138733
1988	89.58147818343723
1989	87.17863475177306
1990	87.3286248442044
1991	86.6811515480717
1992	90.08128408272455
1993	95.5297679112008
1994	92.67654751525718
1995	94.94707244459147
1996	84.39144999202425
1997	84.67593614360332
1998	86.29703886489821
1999	93.60217138425746
2000	93.92054730622716
2001	92.8419513491958
2002	93.14735805710535
2003	89.99276149113282
2004	89.79384354702061
2005	93.85692068429238
2006	94.0545710833669
2007	93.99909534100618
2008	94.03210116731518
2009	86.00614802553795
2010	82.56590064210883
2011	89.21058945852995
2012	91.37003841229193
2013	85.35204155244554
2014	87.61218952202046
2015	81.46658014276443