1976 by Edward E. Hammer, an engineer with General Electric, in response to the 1973 oil crisis. Although the design met its goals, it would have cost GE about $25 million to build new factories to produce the lamps, and thus the invention was shelved. The design was eventually copied by others. In 1980, Philips introduced its model SL*18, which was a screw-in or bayonet mount lamp with integral magnetic ballast. The lamp used a folded T4 tube, stable tri-color phosphors, and a mercury amalgam. This was the first successful screw-in replacement for an incandescent lamp, using new rare earth aluminum lattice phosphors to solve the problem of lumen depreciation that would normally occur quickly in such a thin tube; however, it wasn't widely adopted, because of its large size, weight (over half a kilogram), pronounced 50 Hz flicker and 3-minute warm up time. It was based on the SL1000 prototype from 1976. In 1985, Osram started selling its model Dulux EL, which was the first CFL to include an electronic ballast. Volume was an issue in CFL development, since the fluorescent lamps had to fit in the same volume as comparable incandescent lamps. This required the development of new, high-efficacy phosphors that could withstand more power per unit area than the phosphors used in older, larger fluorescent tubes. In 1995, helical CFLs, manufactured in China by Shanghai Xiangshan, became commercially available. They were first proposed by General Electric, who saw difficulties bending glass tubes into spirals using automated machinery. Xiangshan solved this problem by bending the tubes by hand, made possible by the then-low labor costs in China. Since that time, sales steadily increased. The phosphor coating in spiral CFLs is uneven, being thicker at the bottom than at the top, owing to the effect of gravity during the coating process. Although their popularity varied across countries, in China CFLs were the "dominant technology in the residential segment" in 2011. The rise of LED lighting, however, significantly affected CFL sales and production. As a result of decreasing cost and better features, customers increasingly migrated toward LEDs. In India, "nearly 60 per cent of the lighting market in India has been taken over by LEDs" by 2018. LED prices fell well below US$5 for a basic bulb in 2015. In the United States, CFLs were also facing the possibility of proposed regulations for 2017 that would create difficulty qualifying for