That is due to Bashar al-Assad's regime killing relations with other countries, starving their people, and attacking them. The reason the population has dropped so low is because of refugees migrating to Western European countries, like Germany, and occasionally the United States.
JetPunk doesn't recognize the short name of Czech Republic as "Czechia" so it wouldn't have even got in this quiz, even if they somehow gained 10 million.
albania, North macedonia, bolivia, Mongolia, serbia, bulgaria, slovenia, slovakia, syria, next time make sure all the countries are in before creating a quiz
Austria?