My estimation is 15-17 deg per side, but I believe they are done by hand and can vary from knife to knife. The factory edge is for sure sharp, but is very thin and does not last long for me.
I personally sharpen my Farmer and my Tinker at 25 deg per side. They have thin blades that cut like the devil even at a more obtuse angle, and the higher angle helps them stay sharp longer.
My Bantam and the small blade on my Tinker get 20 deg per side as they see little tough use, mainly opening envelopes and packages.