Usage tracking will not really give you the number of logins. You can of course define what you consider a new login (when time between 2 executions is over 10-15 minutes for example), but it's just an estimate of the number of logins.
For a real official count you would need to parse log files which contains logins, or enable extra logging on the server which is supposed to give you some more precise figures.
But usage tracking is probably enough if you look for an approximate number of logins (if you are maybe tracking good users vs bad users never logging in).
Good point ... track usage of the information (that's where the value is) ...
I yield to the experts here ... but, if you must provide this, a quick way would be to use GREP (possibly AWK/SED too) on the saw logs. I had done this in the past just to get a sense if anyone was actually logging in to our application . The saw log should say something like " user XYZ logged in|logged out. You could put this output into a CSV file, and ultimately in Excel then. Then, use an excel function to count ...
I came up with something like this (user ID's are "blacked out"):
If I have some time later, I'll see if I can build a command for this (I don't remember exactly what I used ...)
One other thing, I was thinking. Take a look at: Identify User Or Program That Removed The Users In Embedded LDAP (Doc ID 2279833.1). Although it isn't meant primarily for this, I do see that you'd get an entry for each successful login.
In the log you'd see something like this:
#### Audit Record Begin <Jul 19, 2018 11:32:41 AM> <Severity =SUCCESS> <<<Event Type = Authentication Audit Event><OBIEE_USER><AUTHENTICATE>>> Audit Record End ####
As Gianni has pointed out, You're still going to have to parse a log in some kind of way.
PS - Nice thing about this is that it may also serve as evidence (for an audit) if/when you remove a user's account ... assuming you're using the WebLogic LDAP.