[3.23 and below]
In this analysis it is important to compare the number of active users in the system to the number of accesses in the last 30 and 90 days.
To check the number of users, go to Settings > User Management > Users
System access history is in Reports > System access > Access history and select a date range. In this case the interval is 30 days.
In the case below the interval is 90 days.
For example, this vault has 197 active users, but the access history of 30 and 90 days reports 81 and 149 users accessing the system respectively. So 116 users have not accessed the vault in the last month and 48 have not accessed at any time in the last three months.