What is Keyword density
Keyword density is the percentage of times a particular keyword or phrase appears on a web page compared to the total number of words on that page. Using this concept you can get your better rank for your website.
Best percentage of keyword density
According to me less than 7% is better for your website, but i will suggest you maintain keyword density on your website upto 5%.
K.D = number of keyword / total number of words on page *100
You can check keyword density on your website online Click Here.