While more than 700 people have died in these attacks, positive identification of the victims, either by Pakistani or US authorities, has been made in fewer than a dozen instances.
Pakistan has consistently argued that drone attacks are hindering rather than helping with the battle against extremism, saying they fuel public anger against the government and the US and boost support for militants.
More than 700 people have been killed in such attacks under Mr Obama, compared with slightly fewer than 200 from under his predecessor, George W Bush.
The militant backlash over the same period has been even more violent. Extremists have struck more than 140 times in various Pakistani locations, killing more than 1,700 people and injuring hundreds more, the BBC research shows.
Places such as Swat and South Waziristan which have seen offensives by the Pakistani military are virtually closed to independent media and other groups.