What is Keyword Density and what is the ideal Keyword Density of a page?
Keyword density is the percentage of times a keyword or phrase appears on a web page compared to the total number of words on the page. In the context of search engine optimization keyword density can be used as a factor in determining whether a web page is relevant to a specified keyword or keyword phrase.
This is another misconception on SEO that is not really important, according to Matt Cutts, stop obsessing on keyword density because it is not how you can rank high on Google. What really matters is how natural your article sounds. Try to make your article long enough so you can embed your keywords or phrases naturally.