so ive been playing league for a while

so yeah i have been playing league for a couple of years still love it, still in bronze, but i have a ton of these hextech keys and no chests, although i am grateful for having them, i feel like the percentage of them dropping has become unequivocly 0%. I just cant seem to get them with s and s+ grades. Seeing if they possible changed the distribution system for them. Thanks for bothering to read my rambles.