Year	% of total
1976	0.165116503290787
1977	0.179569764137133
1978	0.162086437371939
1979	0.162123753388778
1980	0.208959965907622
1981	0.204353612592496
1982	0.199528220217418
1983	0.286347570205084
1984	0.465924973208902
1985	0.521928423084367
1986	0.59550119456195
1987	0.596974815857066
1988	1.07685951353038
1989	1.94508676660011
1990	3.97952648133082
1991	5.31091043510768
1992	5.18023554364403
1993	4.69511688729146
1994	4.52902848497695
1995	5.49178753775228
1996	6.07835358567826
1997	6.86788138076218
1998	6.68467433214554
1999	6.92732522370973
2000	7.79170823706963
2001	8.56102027834328
2002	9.48609343837891
2003	10.4473161241446
2004	9.18989571005763
2005	8.89844395250771
2006	9.46262103339955
2007	7.90900978666167
2008	8.32374798177319
2009	12.1613687071536
2010	15.7674520242899
2011	14.6609060731362
2012	13.6454160874341
2013	12.9942565817783
2014	13.1003329937105
2015	12.9140862275481