Year	% of total
1970	1.2198890363671797
1971	1.016195175666358
1972	0.9281651572180878
1973	0.8006971446165215
1974	0.7262580537561322
1975	0.6093006094788885
1976	0.3260999286588147
1977	0.4229488109963017
1978	0.4507138351794493
1979	0.6545584333632882
1980	0.7460941279475183
1981	0.9821563233423536
1982	1.1577030868054057
1983	1.305401810810208
1984	1.1378732561153853
1985	1.2598148065239074
1986	1.5508816109522636
1987	1.7320540489842753
1988	1.9649014244844838
1989	1.880302985299013
1990	2.6518391787852864
1991	2.7454242928452577
1992	2.834008097165992
1993	2.996845425867508
1994	3.144171779141104
1995	2.9073698444895197
1996	2.8398791540785497
1997	2.73224043715847
1998	2.642073778664008
1999	2.6110856619331195
2000	2.5445292620865136
2001	2.4835079549864183
2002	2.3954236682159458
2003	2.354111405835544
2004	2.196102690999072
2005	2.3417172593235036
2006	2.4018084204577566
2007	2.4861878453038675
2008	2.5668738178870574