Add expected HL-LHC sensitivity
Add to the three currently-provided stats (SMBG,EXP,DATABG) a fourth one which assumes the experimental (and maybe theory?) errors on 13 TeV measurements scale with square root of the integrated lumi, up to the expected HL-LHC target lumi (3/ab) (and ignoring the small energy increase to 13.6 TeV or above).