The Netherlands is richer and more prosperous than it thought – due in part to recalculations of the value of the country’s illegal marijuana industry.

National statistics office CBS said on Thursday that gross domestic product in 2015 was €6.6bn higher than expected – a 1% increase taking total GDP to €690bn.

The figure includes an estimate of the amount generated through illegal economic activity and that has been increased from €2.5bn to €4.8bn, mainly due to the production of marijuana.

The original estimate was based on 40% of locally-grown marijuana being discovered by police, but they now say only around 20% is confiscated. This means that marijuana production adds €2.3bn more to the economy than earlier thought.

This could mean than the Netherlands has to contribute more money to the EU coffers – contributions are based on economic size.

However, at the end of next month, the CBS will publish revised GDP figures covering 1995 up to the first quarter of this year which may alter the impact, the CBS said.

In 2016, the CBS said the amount earned in the Netherlands through drugs, prostitution and other criminal activities is some €2.7bn a year.