The most important tool to get information for the runtime behavior of the database is the AWR repository.
The AWR repository is part of each Oracle database since the release 10g, but normally you are not allowed to use these information’s. You need a separate license AND the enterprise edition of the database! And even if you want you cannot buy this license for a standard edition of the database.
So we will go back to the good old statspack, still valid and maintained also for the database version 11g.
You can grep out this information from the data dictionary of the database also with diverse pure SQL scripts, but with statspack you get some more comparable values.