Which? found that customer satisfaction of London Overground was at sixth place (out of 20 train operators) with a satisfaction percentage of 58%. Branding Public presentation is visually associated with TfL design standards, using similar graphic design elements to those used on the Underground. These design standards have been applied to London Overground stations, signage, rolling stock and publicity. London Overground also uses the TfL corporate typeface, New Johnston, on its signage, publicity, and stationery and on its fleet of trains. In common with other TfL services, the Overground is denoted by its own colour, a vivid orange (Pantone 158C). The orange colour was inherited from the former East London line prior to its transfer from Underground to Overground. London Overground lines are shown on the tube map in orange; the map does not use colours to distinguish between the different Overground lines. Like the Docklands Light Railway and the Elizabeth line, the Overground is represented by a double line rather than a solid single line, to distinguish it from the colour-coded Underground lines. The London Overground also uses a variant of the TfL roundel. TfL denotes its different transport modes such as London Underground and London Buses with variants of the roundel device using a range of colours, and the London Overground version consists of an orange ring with a blue bar. The roundel has its origins in a 1933 design by the London Passenger Transport Board and has spawned many variations. All Overground lines are also not officially distinguished by individual names, unlike the Underground. Some services such as the Gospel Oak to Barking line is nicknamed colloquially as the "Goblin". Mayor of London Sadiq Khan in April 2022 pledged that he would invite Londoners to give all Overground lines individual names to reflect their "diverse history" if he be reelected in 2024. Unlike other National Rail stations, London Overground stations which are not served by another National Rail operator now omit the red National Rail "double arrow" logo from signage outside the stations, using only the Overground roundel instead. A few refurbished or new stations on the reopened East London line display the station name in large orange three-dimensional uppercase letters. Passenger numbers Passenger numbers have grown very quickly since the start of London Overground in 2007. There were big increases in 2010/11 and 2011/12 due to the opening of the extensions of the East London line