1. A method in a computing device for assessing keyword usage, the method comprising: providing frequency of keywords during various periods; calculating a frequency impulse score for a keyword, the frequency impulse score indicating amount of recent change in frequency of the keyword; calculating a frequency weight for the keyword, the frequency weight indicating a recent measure of the frequency of the keyword; and combining the frequency impulse score and frequency weight of the keyword to give the recent usage score for the keyword for a recent period.