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Thanx
The frequent visitors to this forum will know that analyzed in-depth info can be obtained right here. The SEO strategy primer discussion [webmasterworld.com] - which I was updating while you posted - is the best way to get a quick overview and contains links to the country discussion for more detail.
MMXI does provide top 10 figures on a per site basis but I am not sure that SEO-newbie will be able to figure out what is search engine traffic and what is not from this example (MMXI-Sweden's current top 10 list):
Unika besökare i 000-tal
1 MICROSOFT.COM 1 886
2 HOTMAIL.COM 1 559
3 PASSAGEN.SE 1 552
4 MSN.SE 1 513
5 AFTONBLADET.SE 1 406
6 TELIA.COM 1 294
7 SPRAY.SE 1 144
8 FORENINGSSPARBANKEN.SE 1 045
9 YAHOO.COM 1 009
10 SWIPNET.SE 999
You and I can figure this out henki, but it takes a lot of local knowledge. That's why I recommend members reading the country threads here at WmW, rather than trying to figure this out on their own.
If you are looking for at least 80%, then you have to look into the country specific discussions. If statistics exist, that's where they are published. As to France, I am fairly sure that you can reach 80% with the ones listed in the primer. But if your client insists on 80%, then there is no other way but to buy the full statistics from either Nielsen/NetRatings or Jupiter/MMXI.
So it is a trade off. If your client can accept a figure somewhere between 50 and 90 percent, then you can make the list at no expense. But if it has to be more precise than that, then you'll have to buy the reports and charge him for it. I have been told that we are talking of $3000 per country, but perhaps it will be cheaper if you want only search engines rather than the full site statistics for a country. You would have to ask these companies for a quotation to find out the exact price.
The Top10 SEs dead sure will bring in 80% of SE driven traffic in any country, what´s the question here?
For Spain there are just 6 SEs listed in the overview [webmasterworld.com].
In France [webmasterworld.com] we have 10.
Perhaps you should visit those forums and ask people over there for sources of detailed info.