 According to the 2001 census, Croats account for 92.0 percent of population of the region, and the most significant ethnic minority are Serbs, comprising 3.4 percent of the population.The largest proportion of the Serb minority was recorded in the Sisak-Moslavina and Karlovac counties (11.7 percent and 11.0 percent respectively), while a significant Czech minority was observed in Bjelovar-Bilogora county, comprising 5.3 percent of population of the county.The lowland regions of Croatia proper are the most significant economic area of Croatia in terms of its contribution to the national gross domestic product (GDP).