Year	% of total
1971	41.38479064529986
1972	41.05749964434949
1973	43.47661753338526
1974	44.061609718039875
1975	43.4002136312491
1976	44.54755925534675
1977	49.64056192698123
1978	47.05356139149819
1979	37.357989221926985
1980	40.88707086910714
1981	41.15843039577622
1982	39.470966421347434
1983	38.97316920638188
1984	33.1247953630969
1985	32.31356621979584
1986	37.63488128375915
1987	37.491721022553676
1988	36.02305772345911
1989	30.6110117220644
1990	29.3416169002198
1991	28.549619318184472
1992	32.37296762694181
1993	32.87800971946101
1994	35.19308477552296
1995	37.33433019622529
1996	37.772821653866565
1997	38.90686217914909
1998	43.85809129487563
1999	46.82640182216319
2000	46.02143180136643
2001	48.3090422994488
2002	46.68975231388575
2003	48.110234524474436
2004	47.53859889748892
2005	47.88554162551609
2006	48.057026988127255
2007	49.172540819492035
2008	46.519458547742545
2009	47.3321731440867
2010	46.9026764212494
2011	48.5985928709735
2012	43.28520998959202
2013	40.5097685076521
2014	40.69539205699172