By April 2014, with cumulative sales surpassing those of the 747, the 777 became the best-selling wide-body airliner; at existing production rates, the aircraft was on track to become the most-delivered wide-body airliner by mid-2016. By February 2015, the backlog of undelivered 777s totaled 278 aircraft, representing just under three years of current production at 8.3 aircraft per month, causing Boeing to ponder the 2018-2020 time frame. In January 2016, Boeing confirmed plans to reduce the production rate of the 777 family from 8.3 per month to 7 per month in 2017 to help close the production gap between the 777 and 777X created by a lack of new orders. In 2018, assembling test 777-9 aircraft was expected to lower output to an effective rate of 5.5 per month. Boeing was expected to drop 777 production to five per month in August 2017.