"Exclusivity rates" refers to the level or percentage of exclusiveness or limited access to something. It indicates how rare or special something is, often implying that it is only available to a select group or individuals.
Whereas in Norway, where advertising and promotion are strictly controlled, exclusivity rates at four months are high (roughly 64 %). (breastfeedingtoday-llli.org)
Than our duration and exclusivity rates would be higher. (cathalekibclc.com)