Good example, war over Serbia. Officially, serbs managed to down one to two planes (it was never really clear what downed the second one - was it a simple mechanical failiure, or was it somehow induced by SAM fire) In addition, a third airplane was confirmed to be damaged in action and, upon returning to base, never flew again. There are two more instances of damaged NATO planes but they can't be confirmed so we'll disregard them here. So, in reality, 2.5 losses.
And that was a situation where the attacker had massive numerical advantage - where it could jam with multiple jammers per radar, attack with multiple HARMs per radar, etc, etc, and all that was 1999 technology versus a mix of very old radar and SAM technology. Most modern piece of AD equipment (sans AAA and short range, low altitude SAMs) Serbs had was Kub-M system, which is mid 70s technology. They also had S-125, which is mid 60s technology. In addition, they had P-12, P-14 and P-40 surveillance radars, which are all, at best, mid 60s technology. Even if certain parts were modernized, nothing was modernized past the end of cold war, when Yugoslavia dissolved and with it, better part of its amry.
20-30 year technology gap and numerical superiority resulted in 2.5 planes downed/neutralized for good. One can only try to deduce what could happen in a situation where there is little, if any, numerical superiority, and a 10-15 year technology gap.