[SQLPlus] Extracting dates per week

[Spider]

We have a database which stores dates of transactions and other associated info.
I want to product a weekly summary for the last year, along the lines of:

Week			# Transactions
-------			---
Week1			40
Week2			86
...
Week 51			55
Week52			22

But don’t want to manually enter the date ranges because I’m too lazy!

Is there any more efficient way of getting the data out of the database?

Thanks for any tips!