Spells and their frequency
The most used spell in Harry Potter is "Expecto Patronum". The dreaded killing spell "Avada Kedavra" is actually fired off 22 times which goes to show that death is indeed a prevalent theme in the Harry Potter series. The fact that "Accio" is used a whopping 33 times makes it pretty clear that wizards can be considered a bunch of pretty lazy bums. :)