I looked up your first reference (Davis and bailing, 2001), someone has taken their graphs (which stopped around 1950), and extended them to the current day (fi

I looked up your first reference (Davis and bailing, 2001), someone has taken their graphs (which stopped around 1950), and extended them to the current day (first graph on https://archive.briankoberlein.com/2017/07/15/a-man-for-all-seasons/index.html https://archive.briankoberlein.com/2017/07/15/a-man-for-all-... ). That looks fundamentally different to the previous cycle. The graph looks right to me.