Bestandslücken
[N=1975,12; 1976,2; 1977,4; 1978,3-4; 1985,9; 1986,3; 1987,3; 1988,5; 1989,6u.9-12; 1990-1992; 1993,1-2u.4-6; 1994,1-4; 1995,2u.5; 1996,2-3u.6; 1997,2u.4; 2000,7-8; 2001,1-2u.4u.6-8; 2002,7-8; 2003,7-8u.12; 2004,7-8; 2005,7-8; 2006,7-8; 2007,7-8; 2008,7-8; 2009,3u.7-8; 2010,7-8; 2011,7-8; 2012,7-8u.11; 2013,7-8; 2014,7-8; 2015,7-8; 2016,7-8; 2017,7-8; 2018,7-8; 2019,7-8]