In 1939, there were 16.6 million Jews worldwide, and a majority of them – 9.5 million, or 57% – lived in Europe, according to DellaPergola’s estimates. By the end of World War II, in 1945, the Jewish population of Europe had shrunk to 3.8 million, or 35% of the world’s 11 million Jews. About 6 million European Jews were killed during the Holocaust, according to common estimates.

Since then, the global Jewish population – estimated by Pew Research at 14 million as of 2010 – has risen, but it is still smaller than it was before the Holocaust. And in the decades since 1945, the Jewish population in Europe has continued to decline. In 1960, it was about 3.2 million; by 1991, it fell to 2 million, according to DellaPergola’s estimates. Now, there are about 1.4 million Jews in Europe – just 10% of the world’s Jewish population, and 0.2% of Europe’s total population.

Measuring Jewish populations, especially in places like Europe and the United States where Jews are a small minority, is fraught with difficulty. This is due to the complexity both of measuring small populations and of Jewish identity, which can be defined by ethnicity or religion. As a result, estimates vary, but Pew Research’s recent figures are similar to those reported by DellaPergola, one of the world’s leading experts on Jewish demography.