High kda but no S rank

I get 27/6/16 & 13/5/14 like in that range on Ekko but i never seem to get S rank my cs isnt awful its around 191 cs per game in a 30 minute match What is the ratio for S rank cause im stuck at lvl 5 Ekko for forever and nothing seems to change i usually get A's and A+'s even A-'s but no S rank Plz inform me of what to do Note my rising started recently u can check Op.gg If your really interested in helping me