The statistic comes from the European Central Bank's study on Cash Use by Household in the Euro Area, published in November 2017.
The report presents estimations of the number and value of cash transactions in all 19 euro area countries in 2016, based on survey result as well as figures on main payments by demographic.
“The use of cash and cards differs according to country, place of purchase, transaction value and consumers’ demographic characteristics. Cash was least used in the Netherlands, Estonia and Finland, where its share in the number of transactions ranged between 45% and 54%.” (p. 19)
“In terms of value of payments made at POS, in all countries the share of cash was much lower than in terms of number of payments. In the Benelux countries, France, Estonia and Finland the share ranged from 27% to 33%.” (p. 19)