There are 495,508 of them - the process of crafting the bibLoad.pl script, and testing it as each component was added, took much longer than I expected. But once it started it took less than a week for it to complete it's work.
Now we are testing random titles to make sure that they arrived safely in FOLIO : https://walter.drew.edu/cgi-bin/folio/test/randomTitles.pl