The absolute number of helicopters downed or written off amounts to possibly 10% of the Russian operational fleet, but as these are likely more advanced variants flown by better crews, that remains a significant dent in capability. Interestingly, it is the relatively modern Ka-52 model that forms the bulk of these losses.
The reasons for this experience, and how the situation has evolved, are of interest to other operators keen to draw lessons on their own approach to rotary-wing operations, especially as the US and others are accelerating new helicopter development.
Why has Russia lost so many helicopters in Ukraine?