It isn't odd - mintage from the Soviet Union era has been pretty much a 'state secret'. You might get mintage for most of the coins that were marketed overseas such as commemorative coins but you will not find it for pretty much most of the circulating / circulated Soviet and Russian coins.
Imagine how bad it would look if mintage figures were released and it suggests massive inflation - people would spread rumors and it gets snowballed.
My partial coin collection
http://www.omnicoin.com/collection/gxseriesMy numismatics articles and collection:
http://www.gxseries.com/numis/numis_index.htmRegularly updated at least once a month.