How can I display the top five observations (by frequency) in a table?

Hello,
I am trying to look at the top five recorded diagnoses (numerically coded) in a very large dataset. But given that the dataset is so large, when I type this command

tab diagnosiscode, sort

I get a very long table and I cannot scroll to the top of the table to see the most frequent diagnoses.

I tried typing

tab diagnosiscode in 1/5, sort

but I get an error message

varlist required

May you help me please. How can I view the five most frequent diagnosis in a very large dataset?