How often does each side win in Rook, Bishop and Knight versus Queen? How often does each side win in Rook, Bishop and Knight versus Queen endings?  It is a 6-piece endgame so the evaluation of each position is known but I could not find statistics on this endgame after searching for a while.  

[FEN "8/8/8/3k4/3N4/2q5/5K2/R5B1 w - - 0 46"]
The best resource I know for endgame statistics is the ICGA spreadsheet at https://ilk.uvt.nl/icga/games/chess/endgames.php. The spreadsheet posted there contains pretty much all 6-man endgames. So for example KRBNKQ is found in row 277 (assuming White has RBN), with the following percentages:

       wtm    btm   
W win 51.35  9.45       
 draw 45.13 49.27
B win  3.52 41.28


So the result is highly dependent on who has the move.

EDIT: Clarifications (1) This is a tablebase based on computer analysis of all possible positions with these 6 pieces. It does not refer to actual games played over the board. (2) The spreadsheet refers to "non-broken positions" which approximates to "legal positions".