I often want to give students a broad view of theoretical computer science, in the beginning of algorithms class or when advising a new student. It is hard for me to decide which sub-areas to talk about and how much emphasis to put on each of them.
Therefore, my question is: What are the main sub-areas of theoretical computer science and what is their relative "size"? Let's say the size is the number of researchers who work mostly in that area.
Of course the division into sub-areas is a clustering problem with no unique answer. I also don't expect people to have precise statistics for the size of each area, but some feeling of the relative sizes is already helpful.