@yogthos Now, this is really good and in-depth article. Just remember that communism in Poland ended in 1989 so the "closing balance" is 1990. Now, if you go to page 8:

"income poverty and expenditure poverty incidence startedto decrease after 1994 and 1995, respectively, reaching levels much below the1990 values by the end of the decade"

Page 9 gives absolute values - the closing balance of socialism is indeed 23.8% below social minimum line.