From 2002, Stanley Gibbons compiled a "SG100 Stamp Index" based on retail and auction prices for the "top 100 most frequently traded stamps" in the world. The index appears on the Bloomberg Terminal but was discontinued and given heritage status. In 2004 they also launched an index of 30 rare British stamps. In 2012 the company launched the "GB250 Rare Stamp Index" 'to provide a broad view of the investment market for Great Britain stamps', listing the type of stamps they would recommend for investment purposes. The GB30 and GB250 indices are listed on both the Bloomberg Professional service and Thomson Reuters. According to Stanley Gibbons, rare stamps have averaged an annual compound return of 10 per cent over the past 50 years, however, it is important to remember that this figure has been calculated using backtesting as stamp price indexes are a recent innovation. In addition, the prices in the indexes are based in part on Stanley Gibbon's own retail price lists and frequently traded but low value stamps have been excluded from the index.