18. The system of claim 12 , wherein the keyword ranking providing unit comprises: a keyword ranking determination unit configured to determine the keyword ranking using the total query count of searching for a plurality of keywords which are determined via the regular expression.
18. The system of claim 12 , wherein the keyword ranking providing unit comprises: a keyword ranking determination unit configured to determine the keyword ranking using the total query count of searching for a plurality of keywords which are determined via the regular expression. 19. The system of claim 18 , wherein the regular expression establishment unit is configured to establish a search query which consists of the extracted common affix or a combination of the extracted affix and words.