Since there's no compensation for mining levels, as it doesn't get any easier to succeed. Can higher levels of mining give a percentage to striking mulitple loads per success. The higher your mining level the higher percentage you have to getting 2, 3, 4, or more ores per success.
Maybe at certain levels you are guaranteed a minimum amount, so after reaching level X you get 2 per success and a chance to get more, level Y 3 per load, etc. The higher your levels go and the minimum base changes the maximum amount of ores per success increases, so a level 1-10 miner might get the chance of mining a maximum of 4 ores per success, where as a level 31+ might get a maximum of 10 per success. That level 31+ will get a guaranteed of X ores but might get a bonus of any range for a maximum total of 10 ores.