Complex sentence: When Austria occupied Dalmatia there was a revival of the Slav society inside Dalmatia, while the Italian population, according to the Austrian census, decreased from 22% in 1816 to 12.5% in 1853 and a mere 2.9% in 1910.
Split into simpler sentences: When Austria occupied Dalmatia there was a revival of the Slav society inside Dalmatia. The Italian population, according to the Austrian census, decreased from 22% in 1816 to 12.5% in 1853 and a mere 2.9% in 1910.