TAS factors inversely with the square root of relative air density. So, if we're at the altitude giving 35% (or 0.35) the inverse square root of that is about 1.7.
So, back to my quesstimate of half a tonne per second, the correction Fake Pilot quite correctly makes increases this to roughly 3/4 of a tonne per second. (And 350 mph becomes just udner 600 mph TAS).
Add in the suction from the are outside the direct tube that my crude estimate used - and you're going to be back around the tonne.
G