I have a call-to-action on every page asking people to sign up for the newsletter, but the number of people who actually do that are so insignificant that it do

I have a call-to-action on every page asking people to sign up for the newsletter, but the number of people who actually do that are so insignificant that it doesn't matter. Over the past year I've had about two dozen signups, compared to 15,000 people hitting the site. I haven't explored more of the popular avenues for this though, things like "if the mouse moves to close the tab, show a pop up asking for a signup". It might convert but it's not something I'm comfortable doing at this point.