This is the amount that the UK's Office for National Statistics (ONS) estimated that prostitution contributed to the economy in 2012, following a decision by the EU that prostitution and illegal drugs should be counted as part of a country's Gross Domestic Product. The ONS estimates that: about 61,000 people work in prostitution in the UK the average cost per visit is about £67 each prostitute sees about 23 clients per week, working 52 weeks a year - in total about 1,200. Multiply those figures up and you get £5.7bn (which is $8.9bn, or 7.3bn euros).