Single or multiple repository classes?

My database is relatively small, 8 tables, each with less than 5 columns. I use EF. I created single repository class, but now that I think it might not be the right way to use it. Should I have separate repository class for each of my controllers? Lets say I have Products, Users, Unicorns would it be fine to have a single repository class to operate with all of those and instantiate in each of those controllers, or should I create a separate repository class for each of those?