A_Van,
The report states on page 88 that
A distinct group was identified as small pieces of metal that were suspected to be high-energy objects, or parts of them. These fragments were extracted from the Captain from Team A, the First Officer from Team A, the Purser, who was present in the cockpit at the time of the crash, and from the cockpit wreckage (Figure 37). These fragments were found to be ferrous.
Further forensic examinations were conducted on a number of these fragments. The selection was based on size, shape, mass and ferrous properties. In total 72 fragments were selected for further examination. Fifteen of these 72 fragments were found in the remains of the three crew members, one was found in the body of a passenger. The remaining 56 foreign fragments were recovered from the wreckage.
Then, on page 89, after the photo of the fragments that are stated to be characteristic for the 9N314M warhead, the report says that the forensic institute made a composition depth profile by cutting into the fragments with a focussed ion beam and performing x-ray spectroscopy. 43 of the 72 fragments were found to be made of unalloyed steel (which the fragments of a 9N314M warhead are indeed made of). 20 of the 43 fragments had clear deposits of aluminium or glass. The 14 with glass carried the signature of the cockpit glass layers (sodium, zirconium), the aluminium composition matches the aircraft's. A high accuracy composition measurement shows that there are 2 slightly differing unalloyed steel compositions, these elements could for example come from 2 different tubes (the 9N314M warhead has an inner and an outer layer of elements).
A 44th fragment was non-metallic.
Interestingly, on page 89 it says that the remaining (72-43-1) 28 fragments are made of stainless steel, not of unalloyed steel. The report does not say where they might come from.
I think the statistics is as good as it can be: although the missile spewed out many thousands of fragments, only 800 or so hit the plane, but they did so with tremendous energy. Most of them passed right through. The blast tore off the entire nose of the plane. To find some tens of fragments is then quite a bit. Many were found in the crew's bodies.