Since December 2019, Keepers Registry (https://keepers.issn.org/) has been provided through the ISSN Portal (https://portal.issn.org). Keepers Registry aggregates archival status information regarding continuing resources supplied by 13 archiving agencies.
Building upon this achievement, the ISSN International Centre has just developed and published free statistics, i.e. the number of archived resources per archiving agency, the level of archiving stewardship, the number of resources under exclusive stewardship, and the distribution of resources per publisher and per archiving agency. You will find them at https://keepers.issn.org/stats.