Sell population, entire Empire Welfare Index drops? (Golden Rainbow)

It was understood that the "country" Welfare Index would drop if a "country" sold population..but it looks like it changed the entire Empire.

Here is a sample of the countries affected:
Welfare Index 35.72
Welfare Index 35.28
Welfare Index 35.12

Everything was about 51 Welfare Index before the sales, which was just above the Social Security Index level.

Selling countries apparently does the same thing as well. My empire's welfare index is looking to be 13 points lower than what it should be. My only question is: "How long?"

OK. Also have sold countries recently, too.

Not sure about the time..the "Gamemaster" said "a long time"..whatever that means.

i stopped and it recovered in about a 2 days on LU. Ive noticed exchanging pop between slaves also lowers it