Local councils in the Netherlands are expanding their executive boards – there are now 10% more alderman than there were after the local elections in 2010, according to research by the AD.

Most local councils have now put together new administrations since the March vote and the number of aldermen has gone up to 1,144. The main reason for the increase, the AD says, is that there are more political parties fighting for votes and coalitions are getting bigger.

In Rotterdam, for example, six parties have formed a coalition and the number of aldermen has doubled from five to 10. In Barendrecht, where the coalition grew from three to six parties, each party has an alderman, although some will work part-time.

Alderman earn from €64,000 to €137,000 a year, depending on the size of the local authority. Pensions and expenses come on top of that, and aldermen who lose their jobs are entitled to a generous form of unemployment benefit for up to three years.

In total, the wage bill will rise by tens of millions of euros, the AD said.

Research by the NRC, also published on Friday, shows that men still dominate when it comes to the job of alderman. However, Appingedam in Groningen and Gemert-Bakel in Brabant have an exclusively all-women line-up.

By contrast, 94 of the 305 local authorities assessed by the paper have only men on the executive board.

GroenLinks is the clear leader in terms of female aldermen, with 48 out of 87. The fundamentalist Protestant group SGP, which believes women should keep out of politics, has 27 alderman, all of whom are male.