Report for source subnet

Report for source subnet

Hello community,

I'm looking for following report:

I want to see the amount of successful logins per subnet. I can see the client ip and username of all successful logins, so the information is basically ready. 
so for example:
User A - Client IP
User B - Client IP
User C - Client IP
User D - ClientIP
User E - CiientIP

Thats the data i got. What I want is a report telling me: - Amount 2 - Amount 3

Anybody realized something like that?
Thank you and best regards