Power law exponents α as a function of the time since outburst. The symbols represent as follows: circles – this paper; diamonds – Ringwald et al. (1996); squares – Tappert et al. (2012); triangles up – Schmidtobreick et al. (2005c); tiangles down – Tappert et al. (2014). The double exponents for V630 Sgr, V842 Cen, V2109 Oph, V604 Aql and V2104 Oph (Schmidtobreick et al. 2005c; Tappert et al. 2012, 2014) are connected with dashed lines. Our exponent for V842 Cen is also connected by a dashed line to the line between its two exponents from Schmidtobreick et al. (2005c). The α values for the only common object in ours and Ringwald et al. (1996) samples, X Ser, are connected with a dashed line as well. The dot-dashed line represents the value α = 2.33 for a steady-state accretion disk.