Year	% of total
1970	1.7873456715509175
1971	1.8484448523627208
1972	1.918734336277008
1973	1.8759167416163431
1974	2.17266466133554
1975	2.185341115014868
1976	2.228513684765777
1977	2.1104202665697795
1978	2.35386547335091
1979	2.317044335164506
1980	2.1461505388795605
1981	2.4320179509024986
1982	2.3134306724202465
1983	2.4351164643022205
1984	2.5798250678144683
1985	2.7253069989403627
1986	2.6845406626462514
1987	2.796312389692905
1988	2.964512871016899
1989	2.859220757751702
1990	2.5619128949615715
1991	3.430749682337993
1992	5.3977272727272725
1993	6.950672645739911
1994	7.485689123734038
1995	8.55291576673866
1996	8.64953080375357
1997	8.953442101074414
1998	8.673469387755102
1999	9.17062477164779
2000	10.137719969395564
2001	10.199556541019955
2002	9.345490068381634
2003	10.077781535339872
2004	10.10464355788097
2005	9.981285090455398
2006	10.20468703648769
2007	9.81545867879112
2008	10.11148561057817