With no AED, they're zero. You're not going to get them out of VT or VF, which are the two shockable rhythms, without applying an AED on them. CPR only keeps you in that rhythm long enough for either drugs or an AED to be applied.
My real job outside of volunteering is as an ICU nurse. You will not get someone back who's in VT or VF without medication or an AED. All CPR does is buy you time to get those things in place.