19. The article of claim 14 wherein storing the extracted data comprises storing a date, a document type, and at least one trading partner identifier for each document.
19. The article of claim 14 wherein storing the extracted data comprises storing a date, a document type, and at least one trading partner identifier for each document. 20. The article of claim 19 wherein: the predetermined statistical category is defined by at least one parameter selected from the group consisting of a time period, a trading partner, a pair of trading partners, and a document type; and aggregating the stored data according to the predetermined statistical category comprises calculating a number of documents for the predetermined statistical category.