What percentage of changes to your Salesforce production org results in degraded service (e.g. lead to service impairment or service outage) and subsequently requires remediation (e.g. requires a hot fix, rollback, fix forward, patch)?

How long does it generally take to restore service to your Salesforce org after a service incident or a defect that impacts users occurs (e.g. unplanned outage, service impairment)?