Well, on population, Russia is not as big as the whole EU, it is much less: currently, 31% of the EU-25 (142.8 million vs. 458.5 million). But while Russia's population declines faster than any country in the EU-25 (in fact the whole EU-25 is projected to grow until 2025), the EU will most likely absorb another 120-150 million (Romania, Bulgaria, ex-Yugoslavia, Turkey) before Russia. So if Russia joins say in 2025, it will be around 20% of the then-EU: about the same ratio as Turkey would be in 2015, or the last ten new members were to the EU-15.

_{*Lunatic*, n.
One whose delusions are out of fashion.}