This time it is from Alwyn Young:
Measures of real consumption based upon the ownership of durable goods, the quality of housing, the health and mortality of children, the education of youth and the allocation of female time in the household indicate that sub-Saharan living standards have, for the past two decades, been growing in excess of 3 percent per annum, i.e. more than three times the rate indicated in international data sets.
I thank an MR commentator for the pointer. Addendum: Link is now corrected.