Hemoglobin recovery curves including all donor returns, subdivided into age groups below 30 years old, 31 to 50 years old, and over 50 years old and sex. The black line shows the population average. The upper panels show distributions of the donor returns. The lower panels show the average recovery of capillary Hb (∆Hb) as a function of return period (∆T in days). The 95% confidence intervals are shown as gray shading.