The Statistics tab on the Tablespaces drilldown lists performance statistics for database events associated with the selected tablespace. Each row in the list identifies a specific event and provides countsfor the event based on these time measurements:
Interval—Displays the number of occurrences of the event for the most recent monitoring interval.
Rate—Displays the rate per second during the most recent monitoring interval.
Lifetime—Displays the number of occurrences during the life of the event (since the database was activated or performance statistics were reset).