Incremental number on rows of tables on reports

I am trying to create a report that includes a table with meeting dates, attendees, etc during a specific time duration.  I have everything created, but I would like to number the rows of the table to show the number of meetings during that time.  For example, I might set the duration to be the previous quarter and I want the report to show each of the meetings that took place during that time period.  If I held 25 meetings I would have 25 rows on the table. I would like to have each of the rows numbered starting at 1 and going through 25.  I can't seem to create a formula that does this.