The article
https://en.numista.com/catalogue/pieces765.html
in mintage section describes
1991 4% without mintmark
1991 Л 16% Leningrad Mint
1991 М 14% Moscow Mint
Note. Obviously the percentage is from wrongly described occurrence of lines and has nothing to do with frequency as it expected to be. This is not the case of this topic.
Due to note in follows the percentage is omitted in description, though it it present in the article.
Instead of
1991 without mintmark
1991 Л Leningrad Mint
1991 М Moscow Mint
there should be
1991 Л Leningrad Mint
1991 М Moscow Mint
with sending an email to the collectors who marked the non-existing coin, most probably in hurry, that their coin was added to
1991 М Moscow Mint
