That's interesting.It just dawned upon me, there may be actuarial tables/estimates for the very question that started this thread. Just something to ponder.
In the meantime, here is a fun read:
Here is an update (2020) for Fig. 4.
I'm puzzled, however, with the dip in the blue line for Fig. 1. Why would a larger 4km object have a lower percentage of being found than a 2km asteroid? What am I missing?