The birth rates are the only important quantitative measurement that determines immigration and emigration flows on the planet in the long term (think in 1000s of years not just one human lifetime). Nothing can fix this number problem, besides forcing, or better incentivizing, Croatians (or any other countries) to have more children.
No industrialized country has above replacement level fertility. The right wing might fix it, since the current left government can not increase birth rates.
But relatively right wing conservative countries like Poland (1.32 Births per Woman), Japan or South Korea can have even lower fertility rates than left wing Sweden or Germany (1.58 births per woman).
https://en.wikipedia.org/wiki/List_of_countries_by_total_fertility_rate
Note how Israel is exceptional, since it the only modern fully industrialized country with 2.8 births per woman (means above replacement, (exponential) growth).
I wish we had more quantitative number discussions instead of qualitative discussions about imigration. How can we increase birth rates? Cloning? Child Money? Religion?
Are these good/bad?