Keyword Density term explained
Keyword Density is the number of occurrences on the page of key words to total words in the page text which is calculated in percentage.
Some SEOs believe that the more keyword density on the page, the more relevant these words. Others think that there is an optimum density at which the page doesn't look spam to search engines and highly relevant sentence. The optimum value is a value of 3-5%.
In fact, search engines use an algorithm in which the text is divided into passages and the text will be more optimized query (the more relevant) than more full passages it will meet, excluding spam. Visit only 2-3 occurrences of the phrase in the text, in other cases it is better to use synonyms and other word forms of keywords to optimize your page for your keyword.