I don't know what the current stats are, but at one time the Soviet Union was responsible for 90% of the mass in space and 99% of the debris. Soviets launch heavy and dirty.
I'm still more'n a wee bit skeptical that we could ever acheive "critical mass". Space is big, radiation pressure and residual drag effect smaller stuff more. The issue is probability of a spacecraft being damaged by debris prior to its "natural" age. I think the number of satellites that have died in that fashion is exactly 0. I suspect that if space becomes a couple of hundred times dirtier, the mortality rate of satellites might tick up 0.1% or so.
This may just be a backdoor way of trying to stop missile testing by the U.S., now that we are at the threshold of widescale capabilities, ahead of the rest of the world.
You obviously know more about this than I do.
Time will tell ... there is no low for any human being - of that I am confident to state.