The Risk Table for this object has not been computed with
the standard CLOMON2 software but by processing the output from a
Montecarlo run in the 7-dimensional space of the orbital elements
and the secular perturbation on semi-major axis. This is explained
in the paper
Long term impact risk for (101955) 1999 RQ36 by Milani, Chesley,
Sansaturio, Bernardi, Valsecchi and Arratia
(also available on arXiv).