I thought I did give you numbers already, but here's a few more details. Keeping in mind that this is all "ballpark" range.
A fixed gear drive train in good condition is 98%-99% efficient.
Derailleur drive tops out between 97% and 98%, in the right gears at enough power (it does make a difference)
Cross-chaining, using lower gears drops and other issues drops efficiency to the low to mid-90's.
Running without chain oil costs up to 1% efficiency. Elongated chain costs up to 1% efficiency. Bad DR bearings and pulleys allegedly cost another 2% but I'm not sure I believe that, unless they're jammed up or something.