My catalog says, that after a monetary reform in 1955 many reimpressons were made of stamps issued till that year (1949-1955). It also says some reimpressons are very hard to distinguish. On my stamps down there are number in brackets-(29)/(86)/(87)/(88).Guess these are catalogue numbers of the original stamps, so these are reimpressons(?).Is known how many reimpressons were made?

How can I find which year these reimpressons were made?