Complex sentence: In all, more than 30 percent of the Jews in Europe were murdered in the Holocaust; the world's Jewish population was reduced by one-third, from roughly 16.6 million in 1939 to about 11 million in 1946.
Split into simpler sentences: In all, more than 30% of the Jews in Europe were murdered in the Holocaust. The world's Jewish population was reduced by a third, from roughly 16.6 million in 1939 to about 11 million in 1946.