Information was provided in response to a FOIA request.
Since FY2010 thru January of FY2015, the average approval rate for I-601s is 79.6% and the average denial rate is 20.4%.
The average RFE rate is 18.8%.
Since March of FY2013 thru January of FY2015, the average approval rate for I-601As is 70.2% and the average denial rate is 29.8%.
The average RFE rate is 26.2%.
The total number of I-601 decisions issued since FY2010 (over the course of 5 years and 4 months) = 64,826.
The total number of I-601As issued since the program started in FY2013 (over the course of 1 year and 11 months) = 62,973.
The highest approval rate for I-601s was 82.4% in FY2013 (the year the provisional waiver program started). At the same time, I-601A approvals were at their lowest in FY2013 at 63.9% -- This was pre-"reason to believe" guidance so this makes sense. Total receipts for I-601As since March of FY2013 = 74,439.
Read more stats at: https://drive.google.com/file/d/0B_6gbFPjVDoxRExvLW92eXhHUEU/edit