The amount of active ingredients in ecstasy pills in the Netherlands has almost doubled in 10 years, according to the Trimbos addiction institute, which runs a nationwide testing service.

In 2005, there was an average of 81 mg of MDMA in a pill but last year that had gone up to 150 mg, according to the institute’s 2015 monitoring report. The highest concentration of MDMA recorded last year was 293 mg.

In total, Trimbos researchers were asked to test 12,000 drug samples last year, of which some 60% were ecstasy. Some 13% of the samples involved cocaine and 9% amphetamines.

Trimbos says the price of drugs has remained relatively stable. An ecstasy pill costs around €4 while cocaine is €50 per gramme.