Year	% of total
1971	1.1645594406083617
1972	2.289048341379828
1973	2.4245952445960453
1974	2.383211071264657
1975	2.621970963746195
1976	2.2611411015455087
1977	1.9492451346637372
1978	1.7261678748323475
1979	1.0305625795409188
1980	1.0087754158244884
1981	1.033015094508522
1982	0.8332888974991826
1983	0.9126664704566414
1984	0.7361181742032263
1985	0.6121866884110826
1986	1.05339137835411
1987	1.266426903386354
1988	1.124755056047771
1989	0.8143188412597684
1990	0.8751483569380204
1991	0.719844106829741
1992	0.5919354307590866
1993	0.8262698213825024
1994	0.905884588007303
1995	1.7612398906113385
1996	1.6636681214899707
1997	1.6942634853358496
1998	1.8312625766915762
1999	1.6044026375794371
2000	1.916437534711125
2001	2.392999112011221
2002	2.226945128363479
2003	2.1594079814810794
2004	2.1704727962909462
2005	2.030276315827153
2006	1.9345138823490458
2007	1.7565739958329267
2008	1.5282487463397159
2009	1.3551808079224519
2010	1.2312109081531277
2011	1.2816680851944924
2012	1.2313290136456922
2013	1.205524645048461
2014	1.4794637525348073
2015	1.5138823499980454