Complex sentence: The largest single national group consisted of Polish women (40,000), 26,000 Jewish from all countries, 18,800 Russian, 8,000 French, and 1,000 Dutch.
Split into simpler sentences: The largest single national group consisted of 40,000 Polish women. Others included 26,000 Jewish from all countries, 18,800 Russian, 8,000 French, and 1,000 Dutch.