Bestandslücken
[N=1980,2.10; 1981,12; 1982,3.6-8.12; 1983,1-2.5.7.9.12; 1984,2-6.10-11; 1985,1.9; 1987,3.8-9.11; 1988,5.8-9; 1989,4-5.11; 1990,1.3; 1991,3.5.10; 1992,1-2; 1994,10; 1995,9; 1997,4.9-10; 1998,12; 1999,1; 2000,1; 2003,2.7/8; 2006,2; 2008,4.11-12; 2010,1-3.7-8.10]