Variations of various number ratios as a function of ϕ = WR_cb/O, the fraction of WR stars with respect to O-type stars that owe their nature as WR stars to a RLOF episode in a close-binary system. The continuous lines in the 4 lower panels are the models for ϕ_WNL, ϕ_WNE, ϕ_WNC and ϕ_WC equal to 0, 0, 0.3ϕ, and 0.7ϕ respectively (see text). The horizontal strips correspond to observed ratios as reported in Table 3. The green part corresponds to the values of ϕ allowed by the observation, and the red one the excluded values.