How can I provide class numbers for the past 5 years?

The easiest and cheapest method is to...

Use Student Admin > Student Records > Student Classes > Class Lists which will extract the numbers for a single semester for a year. To get 5 years, you'll need to add each semester together, for each year, to obtain the total number.

The other option is to submit a request to TASS Support to pull the data from the database. However, this will incur a cost.