There is no answer to that because science only looks for phenomena that are regular and unchanging in character over time. The lack of explanation in science is not seen as evidence for anything. It is simply the lack of an explanation.
Practitioners of science are free to constrict themselves as such, and much good has come from these constrictions. But if you are unable scientifically to define what is or is not a miracle, then I do not think you are qualified scientifically to dismiss such a thing as having relevance or irrelevance in scientific pursuits.