[seadan83]

Quick googling (could be wrong), thousands bought freedom, approx 4 million were enslaved. It would have been uncommon, ballpark 0.1% (which still seems high to me. The issue is a very large denominator)

[sarchertech]

Slavery was around long before the US existed. In Ancient Rome it was much more common for slaves to buy their way out of slavery..

[seadan83]

Sure, but the context is America. It would have been helpful to make clear you are referring to other systems of slavery (for which i would still want to see data for).

Again, the resources I found in a quick search state about 5M slaves in Rome, and buying freedom was uncommon.