Year	% of total
1970	10.109731892191856
1971	10.382013362824608
1972	10.002887641396095
1973	9.871507761491088
1974	10.434541331623807
1975	10.0004553216846
1976	9.878667702904528
1977	9.638181067626505
1978	9.750907679617105
1979	9.683867290809362
1980	9.651378558276338
1981	9.712858006320209
1982	9.477748319285507
1983	9.289079735404716
1984	8.642484465780171
1985	8.862776477486795
1986	8.717978711749122
1987	8.457422806066841
1988	8.073230677721286
1989	7.975383897409054
1990	2.3142509135200973
1991	2.266124346310285
1992	2.227298686464877
1993	2.1799888205701508
1994	2.103559870550162
1995	2.0696617869762743
1996	2.06286836935167
1997	2.2132796780684103
1998	2.2579026593075766
1999	2.1708352996696556
2000	2.247191011235955
2001	2.2456461961503207
2002	2.232142857142857
2003	2.279981760145919
2004	2.3118766999093383
2005	2.2339027595269383
2006	2.179379715004191
2007	2.2129436325678498
2008	2.0361121782558587