How do I find the average number of times an ID appears in the dataset?

[Emanuele Zanon]

Good evening, I am very new to Stata, and I have a probably simple doubt.

I have a dataset of about 400 000 observations, which includes the following variables.

ID	n_of_appearances
1	2
1	2
2	3
2	3
2	3

Is there a way that I can find the average number of times that an ID appears? In this case that would be 2+3=2.5

[Nick Cox]

bysort ID: gen count = _N
egen tag = tag(ID)
su count if tag

[Emanuele Zanon]

That worked perfectly. Thanks a lot.