All four companies opted to separate FISA requests from national security letters, meaning that they can only be listed in increments of 1000 (if they had lumped both types together into one large number, they could give the number as an increment of 250).
All four companies reported that for the first half of 2013, they received between 0 and 999 national security letters. The number of FISA content requests also falls in that range for all four companies.
However, the metric of accounts covered by these requests varies widely between from company to company. In the first half of 2013, between 15,000 and 15,999 Microsoft accounts were impacted by FISA requests. Between 5,000 and 5,999 Facebook accounts were impacted by FISA requests. For Yahoo, the number of accounts affected by FISA requests falls between 30,000 and 30,999. Finally, Googlereported between 9,000 and 9,999 accounts.