Sadly by default this option is 1. Now I assume some people would not mind going up but I think the majority would actually consider changing it down (for a harder gameplay).
The downside to this options sadly is that you have no fine controls on it in fact almost all settings have issues with finer controls. I think there was a way to double click or something to get finer controls and enter numbers by hand in the past but I can't seem to get it to work with this UI.
I'm hoping before 16 we could get some work on this to give us a much finer control.