Frequency of giant planets as a function of metallicity and mass of the HARPS (top panel), the CORALIE (middle panel) and the combined (bottom panel) sample. Three different functional forms are shown: a complete exponential with linear mass (blue curve), an exponential and a constant (green curve), and an exponential, a constant plus a drop (red curve). The stellar mass is fixed to M_∗ = 1.0  M_⊙.