Meaning of attributes in mbean kafka.server:name=MessagesInPerSec,type=BrokerTopicMetrics:

[Jack Zhou]

Hi,
Could some point me to the documenation for the attibutes of the mbean:
Count, MeanRate, OneMinuteRate, FiveMinuteRate, FifteenMinuteRate.
I just can't figure out their meaning.

Thanks for help
Jack