When giving grades to students, I often find it interesting to disclose some information about the grades distribution. I imagine that it helps to know where one is situated in comparison to others.

I usually don't want to disclose the maximum grade and the minimum grade, the latter obviously for keeping the students that didn't perform well motivated.

I usually end up giving the mean (or the median, should they be significantly different).

Can one do better? Information about quartiles maybe? What are your practices?

If relevant, I am teaching in France where the grades range from 0 to 20. I am interested in different situations: small class (~20) or whole group of students (~200), regular assignments or final exams.

--- EDIT ---

I am interested in keeping the students motivation high. Are there any (research backed-up) studies about that question?