The most expensive prison in the world

That's Guantanamo.  In May, Obama said the cost was $900,000 per prisoner.  Yesterday. two months later, the cost had risen to $2.7 million for each of the 166 inmates, or so says Representative Adam Smith, the top Democrat on the House of Representatives Armed Services Committee. Smith never explained how the cost could have tripled in two months.  He claims the annual cost is $454,000,000. 

He also claims that we have spent $4.7 billion running Guantanamo since the facility opened in 2002. 

Something doesn't sound right. How could we spend $4.7 billion over 11 years, yet have a current annual cost of $454,000,000 which in Smith's view increased the total cost by so much ($28,220,000) in the current year?

Of course, even if the per prisoner costs have not changed from Obama's estimate, they are at least fifteen times as much that in our super-maximum prisons.