none 

Statements about this table:
1 be the number of the series originally air before 1999 with less than 7 episode and a dvd region 2 release date of 2 september 2002
1988 be the original air date for series number 10
the sum of the number of episode that originally air after 1991 with a series number smaller than 21 and a dvd region 2 release date of 26 march 2012 be 10.0
1 be the number of series originally air after 1999 with more than 7 episode and a dvd region 1 release date of 29 april 2013
the sum of the number of episode that originally air before 1991 with a series number smaller than 21 and a dvd region 2 release date of 26 march 2012 be 10.0
series number
number of episodes
original air date
dvd region 2 release date
dvd region 1 release date
1
6
1973
2 september 2002
tba
2
7
1975
2 september 2002
tba
3
7
1976
26 july 2004
11 march 2008
4
7
1977
26 july 2004
9 september 2008
5
7
1979
5 march 2007
6 september 2009
6
7
1982
5 march 2007
27 april 2010
7
6
1983
3 march 2008
27 april 2010
8
6
1985
3 march 2008
9 july 2010
9
12
1987
5 may 2008
18 january 2011
10
6
1988
22 september 2008
12 april 2011
11
7
1989
22 september 2008
12 april 2011
series number
number of episodes
original air date
dvd region 2 release date
dvd region 1 release date
12
10
1990
26 december 2008
12 july 2011
13
6
1991
26 december 2008
21 february 2012
14
9
1992
26 october 2009
17 april 2012
15
9
1993
26 october 2009
24 july 2012
16
8
1995
27 december 2010
tba
17
10
1995
27 december 2010
15 june 2004
18
10
1997
7 february 2011
15 january 2013
19
10
1998
7 february 2011
16 april 2013
20
10
1999
26 march 2012
9 july 2013
21
10
2000
26 march 2012
15 october 2013
series number
number of episodes
original air date
dvd region 2 release date
dvd region 1 release date
22
10
2001
23 april 2012
14 january 2014
23
10
2002
23 april 2012
tba
24
10
2003
tba
tba
25
10
2004
tba
tba
26
10
2005
tba
tba
27
9
2006
tba
tba
28
10
2007
tba
tba
29
11
2008
tba
tba
30
10
2009
tba
tba
31
6
2010
tba
tba