Transport for London figures show that London's trams (Croydon Tramlink) only emit 46 per cent of the CO2 per passenger km of a bus and only 85 per cent of that emitted by London Underground operations. The full figures are (CO2 emissions in grams per passenger km in 2005/06) in reverse order: 47 for Croydon Tramlink, 55 for London Underground, 75 for Docklands Light Railway, 103 for Buses, 124 for Buses and 711 for Dial-a-Ride (Fig. 4, p 31, TfL Environmental Report 2006).