A "--" in the district column means, that the town is a district-free town, i.e. it is by itself a district.
... Anka 1981 Joni Mitchell 1982 Neil Young 1983 Glenn Gould 1986 Gordon Lightfoot 1987 The Guess Who[?] 1989 The Band 1990 Maureen Forrester[?] 1991 Leonard ...