Originally Posted by Brother None 
That's a very confusing statement. 18,000 copies in what timeframe, 3000 copies average of what? Average GOG sales? Average Baldur's Gate sales?
Stop confusing me!
3000 copies - Average PC game sales in Poland in 1999
18 000 copies - Baludurs Gate sales in 1999 in Poland (it was released in Poland in 1999)