In this paper, we construct a natural probability measure on the space of real branched coverings from a real projective algebraic curve (X, c(X)) to the projective line (CP1, conj). We prove that the space of degree d real branched coverings having "many" real branched points (for example, more than root d(1+alpha), for any alpha > 0) has exponentially small measure. In particular, maximal real branched coverings - that is, real branched coverings such that all the branched points are real - are exponentially rare.