Number of retransmission datagrams currently queued by the retransmit
rate limiter (LBT-RM only).

- n (Int32)
- Statistics set index

Number of retransmission datagrams currently queued by the
retransmit rate limiter.

When a source transport attempts to send retransmissions faster that its
retransmit rate limiter allows (set by configuration option
transport_lbtrm_retransmit_rate_limit, default 5Mbps), the retransmit rate
limiter queues retransmissions until they can be sent within the rate limit.
naksIgnoredRetransmitDelay (above) will generally also rise if this count is high.
This method returns a value from the nth set of statistics
encapsulated within this object.