Non-thermal hard X-ray flux for 12 clusters, as measured by RXTE (magenta), BeppoSAX (black), INTEGRAL (light blue), Swift (blue), and Suzaku (red). RXTE and BeppoSAX results are taken from Rephaeli et al. (2008) and references therein. The INTEGRAL results are taken from Lutovinov et al. (2008), Eckert et al. (2008). The Swift results are taken from Ajello et al. (2009), Ajello et al. (2010), Wik et al. (2011). The Suzaku results are presented in Kitaguchi et al. (2007), Fujita et al. (2008), Ota et al. (2008), Kawano et al. (2009), Sugawara et al. (2009), Nakazawa et al. (2009), Wik et al. (2009), Nishino et al. (2010), Kawaharada et al. (2010).