1% of exploratory actions vs 10% for DQN

Hi
[baselines/README.md](https://github.com/google/dopamine/blob/master/baselines/README.md) states:
> Unsurprisingly, DQN performs much better when trained with 1% of exploratory actions instead of 10% (as used in the original Nature paper).

Why is that unsurprising? Is there an explanation why DQN should be trained with 1% of exploratory actions instead of 10%? Or is this is just an empirical result which appears for most of DQN implementations?