According to your link, that is not fact but an assertion of a famous British journalist H. Brailsford (a communist no less) based on his estimated that two-thirds of the population of Kosovo was Albanian and one-third Serbian.
A primary document (again from your source) from that period (not the estimation of a biased journalist who has an agenda) being the Map of Alfred Stead[, published in 1909, shows that similar numbers of Serbs and Albanians were living in the territory. That is 50-50.
German scholar Gustav Weigand's results listed on Wikipedia are not for all of Kosovo (Wikipedia's problem is that its facts can be biased and skewed).
Lastly, I hope demographics are never a basis for declaring secession if so bye-bye Southwest USA.
Proctor, you should review world history, aside from resource demands....demographics are the most common cause for any territorial conflict.
This new notion that race, religion, creed etc should not matter in diversity rich civilizations is a Pollyanna notion and has zero precedence.
It's messianic.
History is littered with precisely how much demographics count with any society that comes in conflict with Islam and the Balkans have been the route of choice for European expansion in that insidious hegemony for a thousand years and those living there know that all too well.