Yes, and it's not linear. You can find all the relevant answers/data in the tables and figures of this paper: Franco, R. S., Yasin, Z., Palascak, M. B., Ciraolo, P., Joiner, C. H., & Rucknagel, D. L. (2006). The effect of fetal hemoglobin on the survival characteristics of sickle cells. Blood, 108(3), 1073–1076.