It's interesting, I get slightly different numbers. For example, in the spinward marches I get a population count of Interval[{92,559,896,270, 123,188,731,073}] at TL8 or lower. Are you accounting for the "PBG" population modifier? For example Junidy in the Spinward Marches should have a population between 30,000,000,000 and 39,999,999,999. 

You do mention Tenalphi has a population of 60 million (that is, 60 million to 69,999,999), so you do account for the pop modifier, but when computing the statistics do you treat that 60-69.9 million as an interval, or just take the lowest value? 

I get the current total population of the Imperium (Allegiance code = Im*) as 18,049,041,349,210 to 21,832,723,838,665. Far from being 11,000 worlds, I count 8988 worlds. This with the travellermap API scraped as of about 20 minutes ago. 

Interesting work, thanks!