Einstein's Photons

The photoelectric effect is a very frequent question in the HSC Physics examination in NSW. A certain amount of confusion has creeped into the examination responses of some students. Suppose that the frequency of the light being used to illuminate the metal is greater than the threshold frequency of this metal. Most students realise that electrons are released from the metal as the photon energy is greater than the work function of the metal. Now, let the frequency of the light be increased while keeping the intensity of the light constant. Does the number of electrons released per second increase, decrease or stay the same? Many students write that the number of electrons released per second stays constant as the intensity of the light does not change. But it does not. As we increase the frequency of the light (keeping its intensity constant) the number of electrons released per second decreases. Why??