Four-yearly Wage Structure Survey Sampling errors Studies undertaken. National total Unidades: % ,Both sexes,Females,Males, ,2018,2018,2018, All studies,0,42,0,6,0,67, I. Less than Primary,5,79,7,9,6,78, II. Primary education,1,38,2,26,1,59, III. First stage of secondary education,1,14,1,49,1,5, IV. Second stage of secondary education,1,13,1,3,1,58, V. Higher-level vocational training courses and similar,1,36,2,05,1,71, VI. University graduates and the like,1,39,1,5,2,28, VII. Graduates and similar, and university doctors,1,33,1,51,1,91, Notas: Fuente: