By 2002, of the 1,032 Boeing 707s and 720s manufactured for commercial use, just 80 remained in service – though many of those 707s were converted for USAF use, either in service or for spare parts. Of the 556 DC-8s made, around 200 were still in commercial service in 2002, including about 25 50-Series, 82 of the stretched 60-Series, and 96 out of the 110 re-engined 70-Series. Most of the surviving DC-8s are now used as freighters. In May 2009, 97 DC-8s were in service following UPS's decision to retire their remaining fleet of 44. In January 2013, an estimated 36 DC-8s were in use worldwide. As a result of aging, increasing operating costs and strict noise and emissions regulations, the number of active DC-8s continues to decline, with the youngest airframes nearing a half-century of age.