Year	% of total
1971	99.86878075451067
1972	99.88459319099827
1973	85.68936751099652
1974	81.79658158963747
1975	83.3650329188003
1976	80.7760260940473
1977	84.70159151193634
1978	81.41165873118003
1979	78.29945433831026
1980	67.90493642067855
1981	62.50874455147177
1982	58.311862310625585
1983	55.87769180572387
1984	44.66477809254013
1985	34.90731793024686
1986	32.14455993134357
1987	45.23893648970939
1988	42.67492562859122
1989	42.88116372736871
1990	47.2290804117446
1991	49.92007485671956
1992	53.880943177425586
1993	52.17276797471688
1994	55.55774342817761
1995	56.83727581481261
1996	49.794429166553215
1997	48.033771389803256
1998	43.74909808071577
1999	28.477988028576945
2000	20.28041510267167
2001	20.97130712008502
2002	12.984092268966513
2003	13.543634302984511
2004	15.197383705345176
2005	10.856152880654799
2006	8.21548702956871
2007	8.635990001845297
2008	8.00381447197514
2009	8.690105133961016
2010	10.482418588172774
2011	4.9121082456343235
2012	5.833710453778747
2013	5.966837615922196
2014	7.387849136703684
2015	7.14207709948673