At any one time, only 5% of the Soviet population were registered communists.

There used to be this joke, if you got 5 people to join the party, you won a Moskvich, which you were free to drive for a year. If you got 10 people to join the party, you got a dacha on the Black Sea in which to vacation with your family. If you could get 25 people to join the party, you didn't have to.