By 1991, the JNA officer corps was dominated by Serbs and Montenegrins; they were overrepresented in Yugoslav federal institutions, especially the army. 57.1% of JNA officers were Serbs, while Serbs formed 36.3% of the population of Yugoslavia. A similar structure was observed as early as 1981. Even though the two peoples combined comprised 38.8% of the population of Yugoslavia, 70% of all JNA officers and non-commissioned officers were either Serbs or Montenegrins. In 1991, the JNA was instructed to "completely eliminate Croats and Slovenes from the army".