By 2011, the population had fallen rapidly to 90,178. This is a decrease of 43,456 people or around 32.5%. While the Albanian population increased its share to 97.45% (87,814 people), the number of the Serbian population decreased to only 624 people, which was still 0.7% of the total population. The proportion of Roma had also fallen sharply to 0.4% (361 people). According to estimates by the Organization for Security and Cooperation in Europe, around 25,000 Serbs and 6,000 Roma lived in the community before the Kosovo war.[3] The strong population decline of the non-Albanian population is due to their flight and expulsion,[4] especially during the nationwide pogrom-like March riots against the Serb or non-Albanian population by extremist Albanians in 2004, the Serbs who remained in Gjilan used violence been expelled or fled to nearby villages.
Source: Wikipedia