Fuselage lift

Wondering how much if any lift in gliders is generated from the fuselage in flight. There is a famous photo of a F-15 that landed with one wing gone due to collision. This of course was possible due to the lift generated by the F-15 fuselage.

The Schleicher family of gliders had two new fuselages designed in the mid 1990's (ASW-24 and ASH-26). Scheme-Hirth, fuselages take their linage from the original ventus designed in the late 1970's (wing roots added in later designs, tail feathers modified with ventus 2cx.)

Seems like all new designs of gliders focus on the airfoil, wing shape and winglets, but I wonder how much if any design improvements are not realized due to improvements that could be made in lift and drag of fuselage designs.