Year	% of total
1971	10.325466311381804
1972	9.406851959947915
1973	11.705228639096374
1974	9.120406910462158
1975	9.719855767325752
1976	10.646195985151548
1977	11.878155503197577
1978	9.237266607392353
1979	10.229238754325259
1980	10.65882015214583
1981	9.785783836416748
1982	7.538495761140908
1983	7.857343837929094
1984	7.297636103151863
1985	5.3708685626441195
1986	5.561932089909134
1987	5.838106410875716
1988	5.766197996490527
1989	6.070655116404981
1990	4.456467573147291
1991	5.973765356566003
1992	5.793316484133671
1993	5.1109298102481775
1994	3.849684000734272
1995	5.537342362822752
1996	6.833505009832382
1997	6.461603434926445
1998	7.465708844586939
1999	7.241116283963281
2000	6.576292870147124
2001	3.989984839435843
2002	5.202874149256563
2003	7.156019656019656
2004	7.647371216144451
2005	9.863094696625126
2006	9.313876313129093
2007	6.693527726669306
2008	6.3341108917997495
2009	8.187631249852528
2010	10.989416954603733
2011	5.831317593906802
2012	6.925867880375276
2013	9.473170958229819
2014	9.813113985552027
2015	11.614213614541875