Discovered during random drug tests I believe, 18 out of 240 which equates to about 7.5% - very high for the armed forces, the occurance in the Royal Navy has been about 0.4%. What was discovered in this instance is roughly what would have been expected if any work-force of any company in the UK had been randomly tested.

Big difference here of course is that they (Naval personnel involved) will all, quite rightly, be out on their ears.