Weird question: how many of you actually "trace" what you are reading with your finger/pen?

By trace I mean slide your finger under the sentence to track what you are reading. I'm sorry if a more accurate term exists, "trace" is the best I can come up with right now.

Personally, I always read while tracing with a pen as it helps me focus better.

Bonus question for those who do trace: how do you manage with an ereader?