What might account for the dramatic increase in presidential pardons issued by president obama in 2016 and 2017

Requests for clemency

Explanation:

It is true that President Obama, while in his last days in office, has granted clemency to more people convicted of crimes than any president since Truman. The main reason for this record is the increased number of requests for clemency. This, however, is due to the effort of his own administration to shorten prison terms for nonviolent inmates who were convicted of drugs-related crimes.