1. A non-transitory computer-readable recording medium on which a document management program for managing a correction history of a document is recorded, the program making a computer function as: a document store section for storing the document; a correction history table store section for storing a correction history table; a document input section for accepting input of the document which is original and for storing the document inputted in the document store section; a document correction section for correcting a character string of the document stored in the document store section in response to operation input, for registering a correction history including a number of characters deleted by a character string deletion process and a correction history including a number of characters before replacement by a replacement process in the correction history table, and for storing the corrected document in the document store section; and a correction history analysis section for referring to the correction history table to make a decision table including an opacity rate, the opacity rate obtained by dividing a total of the number of the characters deleted by the character string deletion process and the number of the characters before the replacement by the replacement process by a number of characters included in the original document.
5. The non-transitory computer-readable recording medium according to claim 1 , wherein: the document correction section registers a correction history indicative of a character string deletion process, a character string addition process, and a character string replacement process performed on the document in the correction history table; and if a correction is made in the document more than one time, the correction history analysis section divides a total of a number of characters added to a plurality of documents to be corrected and a number of characters replaced by a replacement process by a total of a number of characters included in the plurality of documents to be corrected, and uses a division result in the decision table as a degree of glorification of information indicated in the document.