Institutional vs. Central Repositories: 2 (of 2)

The annual worldwide output of an entire field is incomparably bigger than the annual output of any single institution. So when an institution contains no more than the usual low baseline for annual unmandated self-archiving (c. 15% of total annual research output) it has a much smaller absolute number of annual deposits than a central repository (even though that too contains only the very same low baseline 15% of the annual output in the field as a whole, across all institutions, worldwide). (This is the "denominator fallacy.")