Complex sentence: Successive national governments gave a high priority to the development of a system of (at least) universal primary education; in the late 1930s, as much as one-fourth of the national budget went to education.
Split into simpler sentences: Successive national governments gave a high priority to the development of a system of (at least) universal primary education. In the late 1930s, as much as one-fourth of the national budget went to education.