I am running the trainer with
--do_eval  --report_to none --evaluation_strategy epoch --num_train_epochs 10 

so I am expecting the trainer to evaluate after every epoch and saving those results in either eval_results.json or all_results.json. But those files unfortunately only contain the results of the last evaluation.
It is useful that checkpoints are saved, but I cannot seem to find the evaluation results for each checkpoint. That would be very useful to select the optimal checkpoint.