Questions on hot pixels

I have a lot of colorful 2-3 pixel dots that are red, green, and blue all over my long exposure pictures, and appear in the same place every frame. Google says they may be "hot pixels" but the amount that I have seem excessive. How hot pixels should be expected and what can I do to limit their visibility? Are they due to improper care? Here is an example, with the overall picture and then a few cropped sections. It was a 91 second exposure on my D7100. via /r/photography https://ift.tt/2nyWoYc