What percentage of spam comments is normal?

I’ve had a website for about four months now (WordPress, Bluehost), and lately I’ve been getting about 75% spam comments on my blog posts.

Given that I’m not getting many comments overall, it’s only been a few dozen so far, and I have my website set so that I manually approve comments, so it’s not a huge issue.

But I’m not sure if that percentage is normal or if there’s something wrong with my website/some filter (like Captcha) I can add to discourage that…. I’d welcome thoughts from anyone more experienced with websites than I am!

Here is my website if that’s helpful to see: authorgracemacpherson.com.