Psh, what really needs to be shown in the after-game screen is 'amount of wards placed'
At the moment you can only find this stat on the Match History webpage. It would definitely make people think more about placing wards if they were going to be judged on it after the game. Even players who aren't supports should be placing down a lot of wards. You would be surprised at how FEW wards you put down in a game, probably a lot less than you would think.
You should be shooting for 15-20 wards per player in my opinion. Most people dont even place more than 10 other than supports.
Upgrading your yellow trinket for 250g at level 9 is probably THE BIGGEST contribution you can get for your team.
This trinket upgrade literally makes sightstone unnecessary, for a measly 250g you get a sightstone basically. Getting 4 of these on your team will make an extremely large difference in vision control. Dont be stingy, its the best 250g investment you can get in any game. Generally the jungler should have a red trinket in my opinion. Unless your jungling lee sin or someone else who needs to ward hop.