Using data provided by the annual reports of Illinois public libraries and by the Illinois state library, this publication is a companion to the November 1982 issue of "Illinois Libraries," which enumerated the 16 data elements upon which the analyses are based. Three additional types of information are provided for each of six population size groups, each of 18 regional library systems, and for the state as a whole: (1) the mean, range, and quartiles of each of the 16 data elements; (2) l7 ratios and percentages for each library based on these data elements; and (3) the means, range, and quartiles of each of these 17 ratios. The 16 data elements reported both for individual libraries and in the summaries by population, library system, and the state as a whole include population served, nonresident family fee, hours of operation, total circulation, total staff, book volumes added and held, number of periodical titles currently received, assessed valuation, tax rate, local government and other receipts, wages and salaries, expenditures for library materials and operations, and total operating and capital expenditures. Twenty-two graphs and charts are included. (LMM)