The Number of Estimates (NUMEST) variable in the IBES Summary History file contains the number of estimates that were used in the calculation of the summary statistics. This number does not include what IBES considered to be outlier estimates of analysts, however. These outlier estimates would be excluded from the Summary Statistics calculation and put in the Excluded Estimates file. Also, an analyst that stopped coverage of a company would have an entry in the Stopped Estimates file, and their previous estimates would not be included in the Summary Statistics calculation. So, there may be more analysts covering a company in a given month than what is indicated by the NUMEST variable.
To get the total number of analysts that covered a company at some point during the course of a year, you would want to merge the ANALYS variable from the Detail History, Excluded Estimates and Stopped Estimates files, by ANALYS, ESTIMATOR and YEAR (which you can create).
Then PROC SORT the data with NODUPKEY (no duplicates) BY ANALYST