T2 instance CPU Credit Usage & Balance
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/t2-instances.html
CPUCreditUsage
(Only valid for T2 instances) The number of CPU credits consumed during the specified period.
consumed 消耗
CPUCreditBalance
(Only valid for T2 instances) The number of CPU credits that an instance has accumulated.
accumulated 累積