Get the total number of users connected to a client access server in Exchange 2013

In Exchange 2010 the Get-LogonStatistics was used to retrieve the amount of active users connected to Exchange - although in Exchange 2013 this cmdlet was removed and hence we must use an alternative method.

Figures can be pulled from Exchange performance monitors counters using Powershell as follows:

Retrieve total MAPI clients (e.g. Outlook etc.)
Get-Counter "\MSExchange RpcClientAccess\Active User Count" -SampleInterval 3

Retrieve total OWA clients:
Get-Counter "\MSExchange OWA\CurrentUniqueUsers" -SampleInterval 3