I once had a math professor who said that although they might not admit it, most mathematicians try to solve the Riemann hypothesis in their spare time. How true is this? Who is trying to solve the Riemann hypothesis? I don't just mean "are you?" (although feel free to speak up if you are) but more generally: how big is the group that is trying to solve this? I suppose this strongly depends on how you define "trying"; I can imagine a lot of different levels of "trying it seriously".