I never thought about this.. Generally it should be 5-6%...

5-6% seems a little low to me. Does anyone else have an opinion or better yet, have conducted analysis on the subject?

I read a Backlink ebook recently and it says this about creating the anchor text;

Is this correct? I thought the purpose of having a keyword in your domain is so you can rank for that specific keyword. I don't quite understand why you shouldn't built anchor text to the keyword in the domain or how will you be able to rank for that keyword.

I personally go the 60/40 route - 60% main keyword, 40% secondary keywords. But I'll also throw in links that have my site's address as the anchor text ('www.xyz.com'), and common terms like 'click here', 'my blog', 'my site', etc.

But don't obsess over it too much. Unless you have thousands of links with the same anchor text, it wouldn't cause too many problems.

Don't stress about the analysis.

Because even if you somehow figure out from your countless SEO tests (which takes a ton of time and effort), Google might change it all over again, leaving you in the dark.

If you want natural looking anchor texts

http://www.websitename.com
click here
anchor text
secondary anchor texts (found in Google Wonder Wheel because they're related to main anchor text)
and just find keyword variations in Google Keyword Tool and brainstorm a little (check the keyword count for brainstormed variation keywords) and you're gold

Otherwise, just go 100% same anchor text.

I've heard countless backlink gurus preaching the latter as well.

But, it all comes down to your own experience, which you trust best.