Generally, if you receive less than a 2% unsubscribe rate, you are within industry norms. The one exception is when you send to new lists, as they naturally tend to generate a higher unsubscribe rate than previously emailed lists.
Keep in mind that if your readers are no longer interested in your content, it is best to let them unsubscribe quickly and easily. That way, if they later are interested again, they will be left with a good impression of you.
Obscuring or hiding the unsubscribe link, on the other hand, will just frustrate people and lead to possible spam complaints.