I believe you mean Admitted to a SA. Last year 85 that joined USNA class of 2020 with at least one semester of college. This does not include those from foundation or NAPS. But, there is no published information on how many applied. Not all of the 85 were in NROTC. At my son's battalion he knows of 5 freshmen that applied to USNA and 2 have been admitted. So my answer is 40% (don't believe my number, the sample size is way too small).
If you are just looking for a NROTC nomination to USNA the odds of that happening are very very high.
If OP means getting a nomination as an NROTC college programmer the chances may be high... or they may not, I don't really know. I do know that you will need the endorsement of the PNS at your unit and that no more than 20 can be selected each year to attend the academy.