After I finished work, I will dig through my history and can hopefully deliver.

Update: I spent 1 hour going through my browser history and I was not able to find it. Kinda freaks me out. Sorry.

There are actually some studies that can be found on the internet that suggest that the CTR correlates with the extension shown on the SERP, namely .html is supposedly having a positive impact on the CTR of up to 200%.

I was trying hard to find the website I read it on, but on the quick I couldn't find it. It contained a "study" on it with eyetracking and it made sense.

I've personally never run a test on it, but I decided to add html to our documents by means of Mod Rewrite.

As far as search engines are concerned, it does not matter at all. But overall, the visitor should be more important and seeing that it does not negatively impact rankings, it's worth a try.

After I finished work, I will dig through my history and can hopefully deliver.

Update: I spent 1 hour going through my browser history and I was not able to find it. Kinda freaks me out. Sorry.