8. The non-transitory computer-readable recording medium according to claim 1 , wherein when a condition of a document to be analyzed is inputted, the correction history analysis section extracts correction histories which meet the condition from the correction history table and calculates the opacity rate on the basis of the correction history extracted.
11. The non-transitory computer-readable recording medium according to claim 8 , wherein: the document correction section sets user names of users who input instructions to make a correction in the correction histories; and if a post in an organization which a corrector occupies is designated as the condition of a document to be analyzed, the correction history analysis section refers to a personnel database in which a post of each user in an organization is registered, acquires user names of users who occupy the designated post, and extracts the correction histories including the acquired user names from the correction history table.