Complex sentence: The SKH-SDP appealed to an ethnically mixed electorate; surveys indicated 52% of its supporters were Croats, 28% were Serbs and 17% declared themselves as Yugoslavs.
Split into simpler sentences: The SKH-SDP appealed to an ethnically mixed audience. Surveys indicated that 52% of its supporters were Croats, 28% of them were Serbs and 17% declared themselves as Yugoslavs.