"According to the Crime Survey for England and Wales,238 over the period 2014-2015, 279,000 adults (0.9 per cent of the population aged 16-59) reported the use of NPS. Among young adults (ages 16-24), the prevalence of NPS use was much higher (2.8 per cent), the majority of the users being young men. Herbal smoking mixtures were the most commonly used form of NPS, with 61 per cent of the population aged 16-59 reporting their use. According to Public Health England,239 the number of individuals 'presenting to treatment' for a 'club drug' or NPS more than doubled, from 2,727 to 5,532, between the financial years 2009-2010 and 2014-2015. The largest increase was recorded for mephedrone — from 953 in the period 2010-2011 to 2,024 in the period 2014-2015. Compared with the previous period, the prevalence of past-year use of mephedrone in England and Wales in the financial years 2014-2015 remained stable at 1.9 per cent for young adults and 0.5 per cent for adults, which is similar to the prevalence of past-year use of amphetamines (0.6 per cent) and higher than that of LSD (0.4 per cent) or heroin (0.1 per cent).240"