Income inequalities in a country are analysed with regard to the distribution of standards of living in the population, with the result that any deformations in this distribution over time lead to a diagnosis of increasing or decreasing inequalities. In practice, these deformations in fact generally remain fairly limited in scale: it is rare for growth differences between standard of living deciles from one year to the next to be more than a few points. However, this overall result covers some individual variations that are much greater in scale and number. In France on average, each year, a quarter of individuals see their standard of living increase by 10% or more, and a quarter see it fall by a similar amount. However, when inequalities in standards of living are measured as an average over several years rather than for a given year, this individual mobility can be put into perspective: inequality in the distribution of living standards as an average over five years is scarcely lower than inequality in current living standards.