Calculate replied tickets from the ticket object

Hello,

I am trying to calculate the count of replied tickets - as the metric in the Support Performance overview page in Gorgias app - from the Ticket object of your API.

However, there is no column named replied ticket, count of replies, or similar. Hence, I would like to know what is the logic behind the calculation of the "Ticket replied" metric available in the Gorgias app stats.

Thanks.