How to interpret "processed_call_count" from RPC metric json

Using https://1.1.1.1/proxy/1.1.1.1:12000/rpcz

In collecting RPC connection stats, my data looks like this:

{
“inbound_connections”: [
{
“remote_ip”: “1.1.1.1:38718”,
“state”: “OPEN”,
“processed_call_count”: 17168
},
{
“remote_ip”: “1.1.1.2:43678”,
“state”: “OPEN”,
“processed_call_count”: 15661,
“connection_details”: {
“cql_connection_details”: {
“keyspace”: “keyspace1”
}
}
},
{
“remote_ip”: “1.1.1.3:37442”,
“state”: “OPEN”,
“processed_call_count”: 46869,
“connection_details”: {
“cql_connection_details”: {
“keyspace”: “keyspace2”
}
}
},
}

What is “processed_call_count” ? I assume that is remote procedure call count.
How often does it reset?
If my application makes a connection pool of 20 connections but leaves most unused, are the unused connection generating processed_call_counts? Like a keep alive.