It is estimated UK 492,000 people 8.4% of 16-59 year-olds have used an illegal substance UK yet it is used by 2.2% of 16-59 year-olds yet it is used by 2.2% of 16-59 year-olds 492,000 people 8.4% of 16-59 year-olds have used an illegal substance 1 in 12 of adults