The number of people flying on budget airlines has more than doubled over the past seven years, the national statistics office CBS said on Monday.

In the second quarter of 2017, 7.5 million passengers flew from or to the Netherlands on low-cost airlines, compared to 3.4 million seven years ago. That means budget airlines now account for 37% of all flights, up on 28% in 2010.

In total, nearly 20.4 million passengers flew to or from the Netherlands in the second quarter of 2017 via Schiphol or one of the four regional airports.  This represents a 10.7% increase over the same quarter in 2016, the CBS said earlier this year.

The budget operators work mainly out of the country’s four regional airports: Eindhoven, Rotterdam/The Hague, Groningen Eelde and Maastricht/Aachen. Roughly 19 out of every 20 passengers at these airports use budget carriers.

However, 7 of every 10 passengers on budget carriers flew via Amsterdam’s Schiphol airport, a total of more than 5.3 million passengers.

Spain was the most popular destination for budget airlines, followed by Britain.