We can do the maths, to find out how many terraforming completions there "ought to" be.
Assumptions:
Statistics:
- Number of planets "being terraformed" in the galaxy right now: 2130. (Source: EDSM search for "terraforming" status, no other qualifiers, 5000 LY search radius)
Calculation:
Number of terraforming projects completed each year = 2130 / 50 = 42 planets per year.
You would, of course, need 42 new terraforming projects kicking off each year too, to keep the numbers in equilibrium.
Assumptions:
- Terraforming takes an average time of 50 years. Chosen because it both fits the "it takes decades" lore and because it's a nice roundish number.
- All terraforming takes about the same amount of time. This might not be a reasonable assumption, as one would logically assume that the "easier" planets were terraformed first, meaning that the current ones are over-represented with the "hard cases" that take much longer or require many more resources to complete.
- The rate of new terraforming projects is constant. That is, there hasn't been a sudden surge in new terraforming projects commencing in the last 50 years or so. Thus, a randomly selected terraforming project is at some random point in time-to-completion, somewhere between 0 and 50 years.
- No terraforming projects have started in Colonia yet. I am forced to make this assumption as EDSM has a limit of 5000 LYs on its planet search.
Statistics:
- Number of planets "being terraformed" in the galaxy right now: 2130. (Source: EDSM search for "terraforming" status, no other qualifiers, 5000 LY search radius)
Calculation:
Number of terraforming projects completed each year = 2130 / 50 = 42 planets per year.
You would, of course, need 42 new terraforming projects kicking off each year too, to keep the numbers in equilibrium.