Try writing mock essays - after five or six, you will know which figures you are most likely to use! You will end up with ten to twelve numbers that you need to memorise. Do not forget sources and years.
Alternatively, just remember general patterns. For instance, it is fine if you just say that vehicle thefts are three times more likely to occur in urban areas than rural - as long as you have got a valid source and year, you don't need to go into very precise level of detail!