CHINA
Source: CIA The World FactbookPopulation
1,349,585,838

China is even in worth situation than the EU and other geographically european countries. China is going to be shocked twice. I.e. In 15 to 25 years for the first time, there will be another heavy shock in 35 to 45 years.
Maybe INDIA is going to step in.
Population 1,220,800,359
Source: CIA The World Factbook