Ins and outs of Gulag

"Although arrests were constant , so too were releases. Prisoners were freed because they finished their sentences, because they were let into the Red Army , because they were invalids or women with small children , because they had been promoted from captive to guard. As a result , the total number of prisoners in the camps generally hovered around two million , but the total number of Soviet citizens who had some experience of the camps, as political or criminal prisoners, is far higher . From 1929, when the Gulag began its major expansion , until 1953, when Stalin died, the best estimates indicate that some eighteen million people passed through this massive system. About another six million were sent into exile, deported to the Kazakh deserts or the Siberian forests. Legally obliged to remain in their exile villages, they too were forced laborers, even though they did not live behind barbed wire."