Evolution of the α parameter as calculated by several studies in the literature along with our result. This work is shown as red filled diamonds. We present the extinction + incompleteness corrected value obtained through a linear fit. We emphasise previous UCM works as blue filled circles. (Pascual et al. 2001; Pascual 2005 fix the α = −1.3 value). The black circles designate several studies from the literature: at z< 0.1Gunawardhana et al. (2015); at z ~ 0.24Westra & Jones (2008), Ly et al. (2007)z< 0.4, and Ly et al. (2011)z ~ 0.8; and at z ~ 2.24An et al. (2014). The evolution from Sobral et al. (2013) at z ~ 0.4,0.84,1.47,2.23 is shown as grey filled circles.