Ok, I will play your silly game.
Matt Cutts: Is Keyword Density Dead?
there is one.
Ok, how about Matt Cutts of Goooooooogle, a Google engineer?
SEO Advice: Writing useful articles that readers will love
As long as it is written naturally, you will have no trouble, if you are just keyword stuffing, you will get into trouble for spam.
But the difference between 1 % density and 12 % density, as long as it makes sense will make NO difference on your rankings.
Now, as a professional
SEO for going on 8 years now. Having an annual budget to find the limits and to test the algos on a daily basis, working for major online retailers and placing well over 200 websites into the top 10 for hundreds of thousands of keywords, I can back up anything that I will tell you about
seo. I do not speculate. I am here to help, not guess~!