wolsneRipTidejust keep track of time since start of game and damage dealt and do the division in your head whenever you need to check
on a serious note though this would be a good implementation because csgo has a similar thing called adr
But ADR works in the same manner as stated in a previous comment. It runs off of plugin usage, and isn't displayed on your hud by default, and there is no standard in-game option to enable it.
what u can see ur adr in the scoreboard graphs shit