If you have a keywords database open, you can export its data using File | Export data...
This will export a list of the text files, followed by a list of the words in the database
then the details of each word with the number of each file it is found in and the frequency; thus in these data,
A'S was found in 3 text files (file 40, 162 and 244 listed above) and in each of those text files it occurred three times. The list is formatted with tab characters between each pair so you could import the data into Excel if required.