Year	% of total
1970	7.656620369394148
1971	7.852210002593433
1972	8.158231947248778
1973	7.608702545977082
1974	7.54212354765573
1975	7.834183968043552
1976	7.524079989483928
1977	7.05358288664036
1978	6.383985397999442
1979	6.519637138002979
1980	5.665454131920649
1981	5.191974735737113
1982	4.237664931006059
1983	3.8083766866934243
1984	3.5114256092593013
1985	3.1370729500848933
1986	3.2768704087049736
1987	3.365539539822205
1988	3.6053285970450584
1989	2.9965015100088337
1990	14.285714285714285
1991	14.102564102564102
1992	12.82051282051282
1993	12.82051282051282
1994	12.658227848101266
1995	11.39240506329114
1996	12.345679012345679
1997	12.345679012345679
1998	10.975609756097562
1999	10.843373493975903
2000	10.843373493975903
2001	10.465116279069768
2002	11.235955056179774
2003	9.89010989010989
2004	9.574468085106384
2005	9.375
2006	9
2007	8.653846153846153
2008	8.411214953271028