Reuters reports:

A classified Pentagon assessment shows one in five detainees released from the U.S. military prison at Guantanamo Bay has joined or is suspected of joining militant groups like al Qaeda, U.S. officials said on Wednesday. . . .
A previous Pentagon assessment last April showed that 14 percent of former detainees had joined or were suspected of joining militant groups, up from 11 percent in December 2008. . . .
Two officials, speaking on condition of anonymity, said the new Pentagon assessment showed the percentage had grown to 20 percent. . . .
There are 198 prisoners left at the Guantanamo Bay detention facility, which once held 750, Pentagon officials said. Among those still being held there, roughly 91 are Yemeni.