“…Inequality is a key concept in economics [13], with a large proportion of the literature dedicated to income inequality [14,15], but also focused on wealth inequality [16,17], inequality in education [18,19,20], or inequality in productivity [21], among others, and that can be extended to other variables. In particular, within the framework of the economics of innovation, the efforts have been focused, among others, on the impact of innovation in economic growth [22], the returns to innovations [23], the technological specialization in metropolitan areas [24] or in countries [25], or the role of institutions [26]. However, to our knowledge, there are no previous efforts to measure the inequality in the use frequency of technology codes among the different patents.…”