Vampires have always had a thing for their human counterparts - perhaps because they themselves were also once humans. Therefore, as long as vampires have been around, so have halfbreeds. However, there have only ever been one hundred and twenty eight (128) Svetocha ever born, within the many thousands of years that vampires have been around. That's roughly one (1) every one hundred and seventeen years (117)!
Nobody knows why the female offspring of vampires are so rare. Female halfbloods of wolves survive perfectly fine, are just as common as the male half bloods and live long, healthy lives. For some reason that nobody can explain, this is not the case with Svetocha, however.
In the modern day (2012), only three Svetocha are known to live - a record in itself, as there have never been more than two svetocha ever recorded to be living during the same time period.