Year	% of total
1970	1.9484775012462763
1971	2.0419112054558
1972	2.2927971129243474
1973	2.5723327250075037
1974	2.864071802827781
1975	1.0649377892896799
1976	1.0847108399706866
1977	1.2057643084185876
1978	1.5602055013618812
1979	1.8811376105657414
1980	3.4602065143818805
1981	3.2958812703819977
1982	3.9648939392853673
1983	3.756811996542965
1984	4.739417636638534
1985	6.903099180247582
1986	5.720127170684916
1987	5.926967263736461
1988	5.266335728960883
1989	5.347762608805908
1990	14.23076923076923
1991	14.233576642335766
1992	14.634146341463413
1993	14.61794019933555
1994	14.920634920634921
1995	14.634146341463413
1996	14.792899408284024
1997	14.899713467048711
1998	15
1999	15.549597855227882
2000	15.18324607329843
2001	15.789473684210526
2002	16.22340425531915
2003	16.844919786096256
2004	17.2972972972973
2005	18.428184281842817
2006	18.06282722513089
2007	17.974683544303797
2008	17.69041769041769