Minorities in Greece are small in size compared to Balkan regional standards, and the country is largely ethnically homogeneous. This is mainly due to the population exchanges between Greece and neighboring Turkey (Convention of Lausanne) and Bulgaria (Treaty of Neuilly), which removed most Muslims (with the exception of the Muslims of Western Thrace) and those Christian Slavs who did not identify as Greeks from Greek territory. The treaty also provided for the resettlement of ethnic Greeks from those countries, later to be followed by refugees. There is no official information for the size of the ethnic, linguistic and religious minorities because asking the population questions pertaining to the topic have been abolished since 1951. The main officially recognized "minority" (μειονότητα, meionótita) is the Muslim minority (μουσουλμανική μειονότητα, mousoulmanikí meionótita) in Thrace, Northern Greece, which numbered 120,000 according to the 2001 census and mainly consists of Western Thrace Turks, Pomaks (both mainly inhabiting Western Thrace), and also Romani, found particularly in central and Northern Greece. Other recognized minority groups are the Armenians numbering approximately 35,000, and the Jews (Sephardim and Romaniotes) numbering approximately 5,500. Religious minorities The Greek constitution defines the Eastern Orthodox Church as the "prevailing religion" in Greece, and over 95% of the population claim membership in it. Any other religion not explicitly defined by law (e.g. unlike Islam and Judaism, which are explicitly recognized) may acquire the status of a "known religion", a status which allows the religion's adherents to worship freely, and to have constitutional recognition. After a court ruling, the criteria for acquiring the status of a "known religion" were defined as being a "religion or a dogma whose doctrine is open and not secret, is taught publicly and its rites of worship are also open to the public, irrespective of whether its adherents have religious authorities; such a religion or dogma needs not to be recognized or approved by an act of the State or Church". This covers most religious minorities such as Roman Catholics, Evangelicals, Pentecostals, Seventh-day Adventists, Methodists, and Jehovah's Witnesses. All known religions to be considered by the Greek state legal entities under private law must establish an association, foundation, or charitable fund-raising committee pursuant to the Civil Code. The Roman Catholic Church refuses to be considered a legal person under private or public law and has requested recognition by its own canon law. In July 1999, following a parliamentary amendment, the