Title: United States Air Force.
Question: When did the B-2A aircraft enter into service of the US Air Force?

Title: Religion in ancient Rome.
Question: What did the patrician electorate keep in spite of a new plebeian nobility?

Title: Financial crisis of 2007%E2%80%9308.
Question: Per Bernanke, how much did the U.S. current account deficit increase between 1996 and 2004?

Title: Hunter-gatherer.
Question:
How long has this cultural diffusion been happening?