National parks in the Netherlands were defined in the 1960s as: "Areas of at least 1000 hectares, consisting of natural terrains, water and/or forests, with a special landscape and flora and fauna. There are good possibilities for recreative use. In the national parks, nature care and nature development is intensified, nature and environmental education, nature oriented recreation and research are stimulated." The first national park, in Schiermonnikoog, was however not established until 1989.
... out with 26.0% under the age of 18, 9.4% from 18 to 24, 34.6% from 25 to 44, 19.4% from 45 to 64, and 10.6% who are 65 years of age or older. The median age is 34 ...