How much of the world could die without civilization ending?

[Rafael]

I'm more thinking of what it would take for civilization and technology to pretty much stop advancing for the most part. There'd be a point where people aren't producing and culturefying and instead scavenging on the old system. I'm pretty sure the percentage is significant, in the ballpark of 50% imo.Anything less and a lot of the hits would probably even be good for humanity as a whole.