I need an Excel formula written

I have an Excel sheet with a list of 2 200 Page URLs. I want to a apply a formula so that I can summarise how many unique domains these 2 200 Page URLs are originated from. Some domains are listed as http://example.com and http://www.example.com so I want this to be summarised as one domain.

The document is in Google Docs and I can share the document with who ever is able to write this formula and create a pie graph summary for me.