Durham it became a widely used electric lamp with 3000 or so reported by the company in use in 1900 However, by 1910 there were only 2055 electric lamps of all types in use about 0.25% of all safety lamps. In 1911, an anonymous colliery owner, through the British government, offered a prize of £1000 () for the best lamp to specified requirements. There were 195 entries. It was won by a German engineer with the CEAG lamp, which was hand-held and delivered twice the illumination of oil lamps, with a battery life of 16 hours. Awards were made to 8 other lamps that met the judges' criteria. Clearly this stimulated development and over the next few years there was a marked increase in the use of electric lamps, especially the CEAG, Gray-Sussmann, and Oldham, so by 1922 there were 294,593 in use in Britain. In 1913, Thomas Edison won the Ratheman medal for inventing a lightweight storage battery that could be carried on the back, powering a parabolic reflector that could be mounted on the miner's helmet. After extensive testing, 70,000 robust designs were in use in the US by 1916. Early electric lamps in Britain were hand-held as miners were used to this and helmet lamps became common much later than in countries like the US where helmet (cap) lamps had been the norm. Nowadays, safety lamps are mainly electric, and traditionally mounted on miners' helmets (such as the wheat lamp) or the Oldham headlamp, sealed to prevent gas penetrating the casing and being ignited by electrical sparks. Although its use as a light source was superseded by electric lighting, the flame safety lamp has continued to be used in mines to detect methane and blackdamp, although many modern mines now also use sophisticated electronic gas detectors for this purpose. As a new light source, LED has many advantages for safety lamps, including longer illumination times and reduced energy requirements. Combined with new battery technologies, such as the lithium battery, it gives much better performance in safety lamp applications. It is replacing conventional safety lamps. The Office of Mine Safety and Health (OMSHR), a part of the National Institute for Occupational Safety and Health (NIOSH) (itself part of Centers for Disease Control and Prevention) in the United States has been investigating the benefits of LED headlamps. A problem in mining is that the average age is increasing: 43.3