Break frequencies from the fits to the high-frequency bumps of PDSs plotted against the luminosity. Blue triangles correspond to the first major outburst and red circles to the second major outburst. The fits of luminosity-dependences to break frequency data from the major outbursts are shown. The scaling constant is a free parameter in all of the fits. For the free slope, we get an index of γ = 0.21 ± 0.02. The confidence interval calculated from the fit scatter is also provided (shaded gray).