Get EC2 cloudwatch metric for instance in powershell

Get-CWMetrics.ps1

enum MetricStat {
  Minimum
  Maximum
  Average
  SampleCount
  Sum
}

$metricName = 'CPUCreditBalance'
$instance = 'zzzzzzzzzzz'
$stat = [MetricStat]::Average
$start = [datetime]::Parse('2018-01-01')
$end = [DateTime]::Parse('2018-01-09')
$period = 3600
$stat = Get-CWMetricStatistic -Dimension  @{'Name'='InstanceId';'Value'= $instance} -MetricName $metricName -Statistic $stat.ToString() -StartTime $start -EndTime $end -Period $period -Namespace 'AWS/EC2'
$stat.Datapoints | Select Timestamp, Average | Sort-object Timestamp