Four out of 10 couples have a double income, a report shows.

The Hyundai Research Institute report published Sunday is based on Statistics Korea's annual household survey for 2014.

There were 5,208,000 double income couples last year _ 41.7 percent of the number of married couples.

The figure is up from 39.1 percent in 2006 and 41.1 percent in 2010.

The working couples earned an average of 5.33 million won monthly, 1.4 times the average amount earned by couples with a single income (3.8 million won).

Their average monthly expenditure was 2.94 million won, 1.2 times that of single income couples (2.4 million won).

The couples' spending patterns also differed.

Working couples spent 13.2 percent of their income on their children's education _ 2.9 percent more than the 10.3 percent that single income couples spent.

This is attributed to working couples tending to send their children to private academies during afternoons and evenings when the parents are working.

Single income couples spent 5.8 percent of their income on entertainment and cultural activities, whereas double income couples spent 5.2 percent.

This was because working couples had less time for leisure, the report said.

In addition, single income couples spent more buying groceries while double income couples spent more on eating out, seen as a way to save time.

The report concludes that as the percentage of double income couples increases, time-saving forms of consumption, and child-rearing costs, are expected to rise.

The report calls for policy measures to help related industries grow.