The Decline in Writing About Progress

The frequency of words associated with "progress" in English, German, and French books rose during the era of industrialization, but is down since the 1950s, at least according to google. Is this a signal of declining cultural interest in progress, as a concept? Or just an artifact of how google constructed its text corpus?

This podcast is an audio read through of the (initial version of the) article The Decline in Writing About Progress, originally published on New Things Under the Sun.