I went through
all the courses I teach
and checked for all courses that collect data on both the number
of registrations and attendance.
Then I copy-pasted the data that was easy to obtain
to this document, including a link to where I copy-pasted the
data from.
From this,
I created the data file attendance_rates.csv
(also, from a copy-paste, then some quick ruthless editing).
The plot was created by the script
create_attendence_plot.R.