The reason why that you see below huge decreases in Jewish population in many countries is because they are going in the direction of the Middle East where they did not belong!
Here is a list of countries that had reductions in Jewish population between 1980 and 2020:
Russia= 77%, Ukraine= 92%, France= 16%, UK= 25%, Argentina= 25%, Belarus= 94%, Brazil=16%, South Africa = 83%, Uzbekistan = 97%, Moldova = 97%, Hungary = 18%, Azerbaijan = 83%, Uruguay = 60%, Belgium = 12%, Romania = 73%, Italy = 15%, Iran = 74%, Georgia = 95%.
Here is a list of countries that had increases in Jewish population between 1980 and 2020:
USA= 0.2%, ‘Israel’ = 164 %, Canada = 28%, Australia = 68%, Mexico = 14%, Germany = 242%.