<unk> -device use<unk>  booth, 2008<unk>  is most popular with white females, 16–25 years old, with low-to-moderate skin sensitivity, who know other tanners. Studies seeking to link<unk>  to education level and income have returned inconsistent results. Prevalence was highest in one German study among those with a moderate level of education (neither high nor low). The late teens to early–mid 20s is the highest-prevalence age group. In a national survey of white teenagers in 2003 in the US (aged 13–19), 24% had used a<unk>  facility.<unk>  prevalence figures in the US vary from 30 million each year to just under 10 million (7.8 million women and 1.9 million men). The figures in the US are in decline: according to the Centres for Disease Control and Prevention, usage in the 18–29 age group fell from 11.3 percent in 2010 to 8.6 percent in 2013, perhaps attributable in part to a 10%<unk>  tax" introduced in 2010. Attitudes toward<unk>  vary across states; in one study, doctors in the northeast and midwest of the country were more likely than those in the south or west to recommend<unk>  beds to treat vitamin D deficiency and depression.<unk>  bed use is more prevalent in northern countries. In Sweden in 2001, 44% said they had used one (in a survey of 1,752 men and women aged 18–37). Their use increased in Denmark between 1994 and 2002 from 35% to 50% (reported use in the previous two years). In Germany, between 29% and 47% had used one, and one survey found that 21% had done so in the previous year. In France, 15% of adults in 1994–1995 had tanned<unk> s; the practice was more common in the north of France. In 2006, 12% of grade 9–10 students in Canada had used a<unk>  bed in the last year. In 2004, 7% of 8–11-year-olds in Scotland said they had used one.<unk>  bed use is higher in the UK in the north of England. One study found that the prevalence was lower in London than in less urban areas of the country. Density of facilities<unk>  facilities are ubiquitous in the US, although the figures are in decline. In a study in the US published in 2002, there was a higher density in colder areas with a lower median income and higher proportion of whites. A study in 1997 found an average of 50.3<unk>  facilities in 20 US cities (13.89 facilities for every 100,000 residents); the highest was 134 in Minneapolis, MN, and the lowest four in Honolulu, Hawaii. In 2006 a study of 116 cities in the US found 41.8 facilities on average, a higher density than either Starbucks or McDonald's. Of the country's 125 top colleges and universities in 2014, 12% had<unk>  facilities on campus and 42.4% in off-campus housing, 96% of the latter free of charge to the tenants. There are fewer professional salons than<unk>  facilities; the latter includes<unk>  beds in gyms, spas and similar. According to the FDA, citing the<unk>  Association, there were 25,000<unk>  salons in 2010 in the US (population 308.7 million in 2010). Mailing-list data suggest there were 18,200 in September 2008 and 12,200 in September 2015, a decline of 30 percent. According to Chris Sternberg of the American Suntanning Association, the figures are 18,000 in 2009 and 9,500 in 2016. The South West Public Health Observatory found 5,350<unk>  salons in the UK in 2009: 4,492 in England (population 52.6 million in 2010), 484 in Scotland (5.3 million), 203 in Wales (3 million) and 171 in Northern Ireland (1.8 million).
Indoor tanning
Dipping tobacco
Casualty lifting
Nitpicking
Sun tanning
Bodywork 
Doping in sport
Omental cake