The original text was:
"If you want to track the exact number of immigrants year to year, roll 2D6 for each colony each year, +1 if Upported, +2 if Colonization, +3 if Exoglobalization, +4 if Futures, +5 if Endgame. If you roll 7 + the heliocentric distance or higher add 1D6 to the population scale due to immigration that year (slightly more than doubling the population). Small colonies suffer instability every time an immigration event occurs."
Please use a rule similar to: "Roll 2D6 for each colony each year, +1 if Upported, +2 if Colonization, +3 if Exoglobalization, +4 if Futures, +5 if Endgame. If you roll 7 + the heliocentric distance, the colony suffers instability".
However I'm working quite a lot in this area of the rules for the next update, so may end up with a different rule entirely.