History of the Encyclopædia Britannica the criteria by which the articles were sorted were not obvious even to scholars, despite Dr. Adler's claims that the sorting followed naturally from the "Propædia's" outline of all knowledge. In 1985, the "Britannica" responded to reader requests by restoring the index as a two-volume set. The number of topics indexed by the "Britannica" has fluctuated from 500,000 (1985, the same as in 1954) to 400,000 (1989,1991) to 700,000 in the current 2007 print version. Presumably, this recent increase reflects the introduction of efficient electronic indexing, since the size of the encyclopedia has remained nearly constant at approximately 40 million
Encyclopædia Britannica and recency. In all four categories and for all three encyclopaedias, the four average grades fell between B− and B+, chiefly because none of the encyclopaedias had an article on sexual harassment in 1994. In the accuracy category, the "Britannica" received one "D" and seven "A"s, "Encyclopedia Americana" received eight "A"s, and "Collier's" received one "D" and seven "A"s; thus, "Britannica" received an average score of 92% for accuracy to "Americana"s 95% and "Collier's" 92%. In the timeliness category, "Britannica" averaged an 86% to "Americana"'s 90% and "Collier's" 85%. The most notable competitor of the "Britannica" among CD/DVD-ROM digital encyclopaedias