Cameron Ross at Elsevier points me to a method of checking the number of records in Scopus and the number of abstracts. By using quotation marks as for proximity search ” “ and default fields article title, abstracts, keywords you get the total number of records in Scopus. This screenshot returns 27,490,216 hits:

When checking the number of abstracts you write this “a” OR “e” OR “i” OR “o” OR “u” and limit to abstract field. This screenshot returns 16,485,320 hits: