Year	% of total
1971	4.4458550070944485
1972	2.720244899427806
1973	5.0152102839055095
1974	2.1777301549432195
1975	2.227104867930892
1976	1.9923255190696543
1977	1.2649289244592896
1978	1.503999872621617
1979	1.262747317410227
1980	0.9856227912878426
1981	0.7297908949628377
1982	0.8058738168680236
1983	1.043903678283151
1984	1.484445466336658
1985	2.4071000121398045
1986	3.2231578933526657
1987	5.313167475461053
1988	4.819111402503617
1989	4.443475630057794
1990	7.20355675312701
1991	7.575265621700174
1992	5.684510087132308
1993	6.48027884785886
1994	6.953962434815885
1995	5.422170679835384
1996	5.23205874078305
1997	5.153101709245978
1998	4.806744321425177
1999	4.343805848627066
2000	3.9333872606822
2001	4.5348058529215844
2002	4.135211086795688
2003	3.242419305138833
2004	3.447720632550042
2005	3.4094591308625244
2006	2.3940219156082283
2007	2.2015734622894754
2008	2.0824990365294305
2009	2.0347822082730675
2010	2.448559011794445
2011	2.9493491284128823
2012	2.7820005898112257
2013	3.047020297741955
2014	2.984652031876622
2015	2.9838230121690197