The data that you see on the Product Stats page is today's data ONLY. As your products begin to sell throughout the day you will notice more products appearing.
In order to see more days you will have to use the Smart Search feature to change the date(s). Go to the Main Menu > Product > Product Stats use the Smart Search filter and change the date(s).
How do I see a date range? Within the Smart Search feature select the date dropdown field for the From Purchased Date through To Purchased Date field.