And Poland was officially formed and unified in 1990. Or do you want to go back to the commonwealth and call that Poland even though 80% of the territory doesn't match up with where Poland is on the map today...
The most nonsensical thesis I've heard. But I suppose it's just for fun only.
But still very interesting your percentage calculations. I suppose you took 200 thousand km2 which were saved after the Germans make it possible to annex the eastern part of Poland by Soviets. And you probably divided it by 990 thousand km2 of the greatest extent of the Commonwealth at the beginning of the XVII century. Nice effect. But so what.
The Commonwealth consisted of 2 parts. The more powerful was the Kingdom of Poland. The second part was Grand Duchy of Lithuania where nobility was completely polonized. Even in early XX century the former frontier of Poland (yes!) was well known and shown in terrain by local peasants north-east of Orsha and west of Katyń.
If it wasn't Poland, so Poles are all Martians and Germans maybe from Venus.
By the way, did you try it with Holy Roman Empire in its greatest extent (Italy, Burgundy, the Netherlands) comparing to Bundesrepublik.