1914 population statistics for the Ottoman Empire was collected and published as the Memalik-i Osmaniyyenin 1330 Senesi Nutus Istatistiki. These statistics were prepared by using the figures from the 1905–06 census of the Ottoman Empire and reflecting births and deaths registered in six years from last. The register states that birth and mortality rate used on "nomads" such as the nomadic Nestorians. The Ottoman Court deliberately omitted the Ecclesiastical births and deaths from the statistical figures.
The 1914 census list reflected major changes in the territorial boundaries and administrative division of the Ottoman state. The population statistics and Ottoman general election, 1914 were major population sources. 18,520,015 was the population. The grand total for 1914 showed a "net gain" of 1,131,454 from the 1905-06 Ottoman census survey. The data reflects the loss of territory and population in Europe due to Balkan Wars, as the total net gain figure would be 3,496,068.
1914 population statistics for the Ottoman Empire Wikipedia
As a result of the substantial territorial losses in Europe suffered during the Balkan wars, the total population of the empire fell to 18,520,016, of whom an even larger percentage than before, 15,044,846, was counted as Muslim, with 1,729,738 as Greek Orthodox, 1,161,169 as Armenian Gregorian, 187,073 as Jewish, 62,468 as Greek Catholic, 68,838 as Armenian Catholic, and 65,844 as Protestant. No separate figures were given for Franks.
Capital was an important location due to expulsions from Balkan Wars. Istanbul increased slightly, to 909,978, excluding Franks, with 560,434 Muslims, 205,375 Greek Orthodox, 72,963 Armenian Gregorian, 52,126 Jews, 387 Greek Catholics, 9,918 Armenian Catholics, 1,213 Protestants, and 2,905 Latins.1