Since their entrance to the market in 2003,[1] global use has risen exponentially.[2] In a 2014 survey, about 13% of American high school students reported using them at least once in the previous month,[99] and in 2015 around 10% of American adults were users.[100] In the UK, users have increased from 700,000 in 2012 to 2.6 million in 2015.[101] About 60% of UK users are smokers and about 40% are ex-smokers, while use among never-smokers in the UK is negligible.[101] Most still use traditional cigarettes, raising concern that dual use may "delay or deter quitting".[6] Most peoples' reason for using e-cigarettes involve trying to quit smoking, though a large proportion use them recreationally.[7] It is commonly stated that the modern e-cigarette was invented in 2003 by Chinese pharmacist Hon Lik, but tobacco companies have been developing nicotine aerosol generation devices since as early as 1963.[8] As of 2018[update] most e-cigarettes were made in China.[9] Because of overlap with tobacco laws and medical drug policies, e-cigarette legislation is being debated in many countries.[10] The revised EU Tobacco Products Directive came into effect May 2016, providing regulation for e-cigarettes.[11] As of August 2016, the FDA extended its regulatory power to include e-cigarettes.[12] Large tobacco companies have greatly increased their marketing efforts.[13] As of 2014[update], there were 466 brands of e-cigarettes,[107] with global sales of around $7 billion.[15]