When it comes to contingent government pension liabilities as a percentage of gdp, Poland appears to be above 350%.
France, Denmark, and Germany are next in line, with figures well over 300%. For purposes of comparison, the United States is considered to have a serious pension problem but the corresponding number is only slightly above 100%.
Here is the John Authers and Robin Wiggelsworth FT story. Australia seems to be doing best.
One reason for this high Polish sum is that the Polish government has semi-nationalized a lot of the private sector pension liabilities. In 2014, this procedure (FT) did not receive much discussion:
As part of an overhaul of the country’s pension system, Warsaw will next week transfer from privately-managed funds to the state 150bn zlotys (€36bn) of Polish government bonds and government-backed securities, which will then be cancelled.
I believe this idea will reenter the broader policy debate sooner or later.