Keyword density analyzer has 2 built in filters:
Stopwords are commonly used words such as: the, a, where, how etc. These words are ignored by search engines when searching for keywords. To set Keyword analyzer to ignore stopwords in the analysis, ensure that the Ignore stopwords menu option is ticked in the Options menu. Stopwords can also be toggled on and off by clicking the Ignore stopwords button on the toolbar.
Show as Percentage:
Selecting this option changes the results display to a percentage value of the web page. To display your results as a percentage, ensure that the Show as percentage menu option is ticked in the Options menu. Show as Percentage can also be toggled on and off by clicking the Show as Percentage button on the toolbar.