Is it 20-30 per year or month?
It's per year, but they have the capacity to increase it to per month also, but that's not going to happen anyway. Really, when it comes to the Americans, there's no limit. They can produce all that you can afford and more. IIRC, their highest production rate was 400 per year.
Why it matters that Lockheed Martin is set to launch production of F-16s in Greenville
The first Lockheed Martin F-16 jet should be produced by December 2021 at the South Carolina Technology and Aviation Center.
www.greenvilleonline.com
There's no simple answer to your question actually.
The good news is we will be making the wings. The 90 jets will at least need 180 wings.