I took these data from the Purdue Accessions briefing deck. It appears to reflect the combined Donations of 2LTs from the three Accessions sources: ROTC, USMA, and OCS.
http://www.purdue.edu/armyrotc/_f/currentcadets/accessions_briefing_11_apr_2011.pptx. Click on the link, then click to download the slide deck.
On the left are the five Donor Branches. Across the page is the number of 2LT "lent" in 2011 to the four
Receiving branches.
FY11 Branch Detail Mission
Donors (5)////
Receiving Branches (4)
///////
AR////
CM/// F
A///
IN//// Total
AD //// 2 //// 1 //// 2 //// 4 ///// 9
AG /// 15 /// 25 /// 13 /// 8 //// 61
FI ///// 5 //// 2 //// 5 //// 11 /// 23
MI //// 54 /// 23 /// 44 // 111 /// 232
SC /// 29 //// 11 /// 24 /// 60 /// 124
Total/105/////62/////88////194////449
Legend:
AD = Air Defense Artillery
AG = Adjutant General (HR)
FI = Finance
MI = Military Intelligence
SC = Signal Corps
AR = Armor
CM = Chemical
FA = Field Artillery
IN = Infantry
The seven Branches that do not appear to have Donated or Received in 2011 were: Medical Specialist, Engineering, Military Police, Aviation, Ordnance, Transportation Corps, and Quartermaster.
You see from the above that Military Intelligence was the biggest Donor in 2011. MI donated 232 out the combined 400 2LTs coming out of USMA, OCS, and ROTC in 2011. That's 58%.