Sampling errors Persons who have had casual partners in the last year. Variation coefficient by age group and sex. Units: % ,Both sexes,Males,Females, Total,2.91,3.25,5.60, From 18 to 29 years of age,3.84,4.22,7.22, From 30 to 39 years of age,5.45,5.95,12.09, From 40 to 49 years of age,6.71,7.99,12.82, Notes: Source: National Statistics Institute