Religion in Prisons

Highest of the three "Abrahamic religions,
but don't mention Islam!

A Pew Research Survey of prison chaplains in all 50 US states shows that "America's state penitentiaries bustle with religious activity."  One of the charts [above] shows that Religious Extremism is "very/somewhat" common amongst Muslims (57%), more than double, or up to seven times that of other major religions such as Protestants (24%), Jews (14%) and Catholics (8%).
It's notable in the commentary on these figures that Pew does not mention these figures for Muslim inmates, but only mentions the figures for such as pagan/earth-based, Catholic and Jews.
I wonder why that is, given the clear prevalence of extremism amongst Muslim prisoners perceived by these prison imams....