Generate Summary Report From Range

I have a spreadsheet of website stats showing the number of visitors to all the domains and aliases we use for company websites. Each domain or alias has its own unique row of data. The data is in the order of most visitors. I have attached a simplified and anonymised example of the data in worksheet "stats". In real life this sheet runs to several hundred rows.

As you can see if look at the worksheet "domain key", each of our websites has more than one domain or alias pointing at it - these are reported separately by our stats package.

What I want to do is find an easily sustainable way of generating a summary report each month, such as you can see on the worksheet summary, which will give a total number of vistors for each site calculated from the visitors to the various adresses each site uses.

What I have done so far is use a very long SUMIF function, e.g. to find all visitors to the FR site the function reads:

=SUMIF(stats!A2:A16, "www.companyname2.fr", B2:B16)+SUMIF(stats!A2:A16, "www.othername.fr", B2:B16)

This looks OK in the example above but in the real data we have in some cases over a dozen domains pointing to one site and its very messy and hard to maintain.

What I would prefer to do is something that would use a range of data for the criteria rather than a specified string e.g.:

=SUMIF(stats!A2:A16, domain_key!C2:C16, B2:B16)

Obviously the straight SUMIF function won't do this. The advantage to this approach is that it would make the ongoing management of which domains are counted for each country a lot simpler as I could just edit the data in the domain_key sheet rather than having update the functions.

Some issues to be aware of are:
The order of data will change each month so youcan't guarantee that each address will be in the same row every monthThere isn't a pattern to the addresses that would allow you to use any kind of wildcard, e.g. you can't say all addresses containing "companyname" are the UK site and all addresses using othername are the French site. Similarly, you can't say all the french site addresses end in .fr - some countries use .com