Year	% of total
1971	30.913360642763195
1972	31.76361218725628
1973	33.801334302665396
1974	35.570005961722806
1975	36.25533329635135
1976	37.36786402147403
1977	38.51807282268525
1978	40.177804693241946
1979	41.5905651203782
1980	43.19515401487256
1981	44.254836181998805
1982	44.526809495979165
1983	45.83466384017923
1984	45.3464627725006
1985	45.47038520386392
1986	45.769032039178825
1987	45.732364568924815
1988	45.63255040940639
1989	46.08256058086075
1990	52.21618620512235
1991	51.76152183591673
1992	51.73723733839149
1993	51.36296979228106
1994	51.749634998165035
1995	50.862399189872704
1996	50.702048070815
1997	51.446954696919306
1998	49.64703157503961
1999	47.89610032735531
2000	48.35936424734272
2001	49.05288229889451
2002	49.029879502339405
2003	48.09805334217507
2004	48.31648130871857
2005	48.17013188514394
2006	48.1031721325491
2007	46.681380471951535
2008	48.20306188200098
2009	47.95983004593749
2010	49.24893558340765
2011	44.87493835139633
2012	46.210704161166085
2013	47.565063631439436
2014	39.95254923856784