To get this info, I export the form fill activities, which gives most of the data you would need to keep track of the form usage including date/time, form ID and the URL of the page containing the form in a csv file. As Sanford notes, you will not see the forms that are embedded on pages that nobody ever used to fill the form, but I am OK with disregarding such places. You can use the bulk activity export REST API for this.
... View more