Year	% of total
1971	11.743378960021715
1972	6.616978095038141
1973	7.241294070389024
1974	5.4631166403994476
1975	5.263824665864319
1976	5.282507525018604
1977	4.576683958341583
1978	4.960569152569437
1979	4.242983577074163
1980	3.753049217965275
1981	3.547441045946535
1982	2.7010500430668887
1983	2.517016012898938
1984	1.9164947878923015
1985	2.0208382813064714
1986	5.040370458323438
1987	3.7903713649173025
1988	3.2761564478685443
1989	2.7107794675947874
1990	2.2156798506424438
1991	2.1742747795218813
1992	2.58178478645773
1993	2.4299933326983525
1994	2.4549974811664312
1995	2.721688237705959
1996	3.1784068827717853
1997	3.2131747959296324
1998	3.458296555067941
1999	4.935527432211188
2000	4.347539480095153
2001	4.815103437359212
2002	3.887800827954905
2003	2.9519211503572222
2004	3.130186112896274
2005	2.8975294826974465
2006	2.950848601482817
2007	2.9951903528497326
2008	3.790812128698439
2009	3.140600831114668
2010	3.1149114387924266
2011	2.7824739495671893
2012	3.545267668432786
2013	4.650706711305981
2014	5.997280966255877
2015	5.04425326483877