Year	% of total
1960	8.0078125
1961	6.921258150032242
1962	3.7424025131462133
1963	4.605359496265925
1964	4.593011778640522
1965	4.422849311655142
1966	4.100360088279707
1967	4.486964305695424
1968	3.4290567439885344
1969	3.3526176024279217
1970	3.975711373105221
1971	3.294301970808938
1972	3.1725372163019605
1973	3.0640885700920006
1974	3.526206737779142
1975	3.789400494437577
1976	3.248566808760841
1977	2.685003274394237
1978	3.737048946052161
1979	3.2561529033754018
1980	2.6371699322159645
1981	2.900061091745427
1982	2.574102964118565
1983	2.0842046563502024
1984	2.0172811456504527
1985	2.759450297087449
1986	3.2583834758436256
1987	3.2892008294783857
1988	3.3146169172251403
1989	3.542012464376312
1990	3.077870592948718
1991	2.5556190657045197
1992	2.6131858407079647
1993	2.0741024948212194
1994	3.131819699499165
1995	3.254257095158598
1996	2.4512341972187106
1997	2.1831495444549165
1998	2.1340579710144927
1999	1.6068231611893584
2000	1.2565264195284662
2001	1.0337022503403541
2002	0.9364944241082829
2003	1.551247273293861
2004	1.5510750793091292
2005	2.235486604702023
2006	2.4899819785029287
2007	2.238790564077492
2008	2.307276836158192
2009	2.0543025914634145
2010	2.3750226002141073
2011	2.666570574297642
2012	2.8078132526746202
2013	2.301839673913044
2014	2.321556889555889
2015	2.1538132086624753
2016	1.6337133709572391