The 'ethernetJitter' statistics table contains summarized
information of the results for a conceptual control
row. A rolling accumulated history of this information
is maintained in a series of hourly 'group(s)'.
When ipslaEtherJAggStatsStartTimeId groups exceeds
the rttMonStatisticsAdminNumHourGroups value, the
oldest corresponding hourly group will be deleted and will
be replaced with the new ipslaEtherJAggStatsStartTimeId
hourly group.