Given the lack of data transparency for Russian and KSA production data, what, briefly, is the basis for the assertion that they have passed 50% Qt?
Russian and KSA production are easily available. The transparency issue is not about production but about reserves, technical field conditions, etc., that make judging future production problematic. And that is where the HL method fits in. It doesn't need that other data. It uses historical production data to help you draw a conclusion.