Over the last couple years, the "Magic Number" of programs on the Rank Order List is 8.x. This number is increasing every year. It includes both US grads, and independent applicants.
In the last two years the numbers were 8.23 and 8.52. In contrast, applicants that did not match, pretty consistently had ROLs of only 4-5 programs.
I did a little bit of fancy statistics, and found that using the data since 2004, in 2009, it will be around 8.75, and in 2010, it will be 9. It will probably be more. I used these numbers because since 2004, the numbers have been increasing linearly. However, since 1999, it has been increasing exponentially. Im not good with stats
Anyway, I dont know how the length of the ROL translates to number of interviews attended. The applicant might not rank one or two of the programs they interviewed at. The programs rank 55-60 of their applcants - or about ten applicants per position. Interestingly, programs usually interview ten applicants for each of their seats. Maybe this means that they put almost all of their interviewees somewhere on their ROL?
But, what we can do, is plan to rank 9 or 10 programs.
In the previous year's NRMP report, they included the length of contguously placed specialties on the ROL. It was pretty significant data which showed that applicants who ranked only one specialty, or ranked multiple specialties contiguously, fared much better. A ROL of (IM IM IM IM FM FM) had a better outcome than (IM FM IM IM FM IM FM)