Query: Drug manufacturers paid off doctors a total of how much money?
Context: An investigation by ProPublica found that at least 21 doctors have been paid more than $500,000 for speeches and consulting by drugs manufacturers since 2009, with half of the top earners working in psychiatry, and about $2 billion in total paid to doctors for such services. AstraZeneca, Johnson & Johnson and Eli Lilly have paid billions of dollars in federal settlements over allegations that they paid doctors to promote drugs for unapproved uses.