well, It makes sense, the greater work force, the more production.
So the amount of population is the percentage boost for production, up to 150% (it needs to be capped because of those planets with like 1k pop)
so 80 population will generate an 80% production boost. and 120 would generate a 120% production boost. up to 150%

A Topolis Ring. Size 7 +1000 Population. This is the last tier structure. Does this mean the planets all planets will get 150% bonus??
Too overpowered. Just my opinion.

Topopolis : +1000 Population

Commonwealth, he did say it would cap at 150%.

BUT this is a bad idea. Population already gives you a benefit for your planet. Damage Capacity. It is essentially the same as researched hull and shield modules for your ship. Do those give you any benefit other than absorbing damage? No. Nor should researched population centers. And artifact structures that add population also add to something else, so don't even go there...

Woops~ Editt hehe

Only way I would see this being somewhat ok is if it capped at 100% and was based on the % of the population on the planet. So someone gets rid of 5% you production bonus from this goes down to 95%.

Though it is still not to good of an idea. Maby a set of planet buildings or somesuch.

ok, then the percentage of th4e boost is based off the percentage of the population to the total population, caps at 100% and you need a building to get the production boost, the building would be called worker's assignment facility, it's going to be a an artifact, costs 5k artifact points.
and it's description would be assigns the population of a planet to different production jobs on the planet, provides a percentage production boost based off percent of current population to maximum population.

I' had i similar idea a while ago but was thinking more along the lines of every 100 population gives you a 1% boost with a cap at 10%. Not a lot I know but it means that the rather space hungry topopolis buildings are more appealing as you also get a 10% boost to overall production.