The gender pay gap is defined as the difference between men's and women's average gross hourly earnings as a percentage of men's average gross hourly earnings. The indicator has been defined as "unadjusted" (by the socio-economic characteristics of the working population) because it provides an overall picture of gender pay inequality and measures a broader concept than "equal pay for equal work". Note that if the gap in gross annual wages is analysed, the figure for Spain in 2017 is 22% (compared to 12% for the hourly wage gap), which is mainly explained by the higher incidence of part-time work among women.