Query: What group began to decline within the Empire in the late 19th century?
Context: Until the second half of the 15th century the empire had a Christian majority, under the rule of a Muslim minority. In the late 19th century, the non-Muslim population of the empire began to fall considerably, not only due to secession, but also because of migratory movements. The proportion of Muslims amounted to 60% in the 1820s, gradually increasing to 69% in the 1870s and then to 76% in the 1890s.