You are wrong. The US has about 2 million incarcerated. If 29% of illegals are incarcerated and 100% of the prison population were illegals, then the total illegal population would be 6 million.
30% of 6 million is about 1.8 million
Of course there are more than 6 million illegals and they do not constitute 100% of prisoners, therefore your statistic wrong.
Thanks again for your correction.