I want to know the answer to the following question:
The state oil company NNPC was initially thought to owe how much to the government?
All the background I'm provided with is that "In late 2013, Nigeria's then central bank governor Lamido Sanusi informed President Goodluck Jonathan that the state oil company, NNPC had failed to remit US$20 billion of oil revenues, which it owed the state.". Is that enough to answer the question?