Year	% of total
1971	1.6867338599454693
1972	1.5270487026906723
1973	3.194051340270845
1974	2.9826900752709973
1975	3.2407779002553845
1976	3.507166857804188
1977	2.3562479991290926
1978	2.353370961686735
1979	2.25302868178123
1980	2.1299550308219293
1981	2.05004247077071
1982	1.3266463405389457
1983	2.104999309434415
1984	2.174170569375412
1985	2.43696951612432
1986	2.2727997564113136
1987	2.1134487292510915
1988	2.0923654928684843
1989	1.4537118585184503
1990	1.8621356704950225
1991	1.5694523442132113
1992	1.812396066783063
1993	1.3716359295102096
1994	1.3272239960887595
1995	1.6852669062353356
1996	1.795528729981796
1997	1.872774235168621
1998	2.052240912769889
1999	2.132932916142866
2000	2.8261198402839143
2001	3.139169305461162
2002	2.930339004017643
2003	2.541553222343425
2004	2.4366350060129762
2005	2.314308028389757
2006	2.285612901668064
2007	2.0603566637919863
2008	1.660018106688412
2009	2.0058680065335714
2010	2.604820903386972
2011	3.026022312026304
2012	2.887801884352968
2013	2.8552375457763923
2014	2.7697649262887962