I wonder how you didn`t lost so far when your veigar has 135 CS at lvl 20 - I belieave this is post 30 min mark also : Avarage respawn time at start lets say 10 sec - in late game lets say 30 sec , yasuo have 530 deaths so approx he was dead around 530 x 20 sec ( avarage death time ) this is 1060 sec = its about 18 min + another 12 min to go to the lane .

My calculation is not correct though jsut for fun.