Many people who freelance or who work for smaller companies end up not having an amazing salary, but job experience is job experience. This would be about $40k-$45k a year.
The top designers can make around $60+k a year, this is based on experience, talent, etc...
You can probably expect to find yourself in the middle range for most of your career if you have around 5+ years of experience. This would be about$ 50k-$55k a year.
Now if we look at interior designers, the average varies on the service you are providing, such as architectural/engineering vs specialized or furnishing services. The average is at about $50k without certification, whereas with a NCIDQ certification the average increases to about $70-$75k a year. (lowest average is out of college designers at just over $30k a year and highest is luxury designers at $95+k a year)