>>I have always felt certain anxiety when thinking about my salary and only guessing what my colleagues might be earning.<<

I can tell you that anxiety of not knowing is better than the anger/disappointment/a whole host of other destructive emotions after you do know. Companies don't want to deal with this. It can easily get ugly.

In my case, my boss'boss actually had the balls to tell me that he will not be terrorized by me suggesting there are greener pastures out there. Looking back it was a big mistake. Should have waited for an offer and then use this information.

Moral of the story. Be careful what you wish for.