summarize a variable in panel data

[Sujin Shin]

Hello,

I want to make a descriptive analysis on variables of my panel data. I have attached the data below.

What I want to do is see the frequency of fb_age in the dataset. However, as you can see in the data below, the number of observations per h_pid differ and I want stata to count only once for each h_pid.
For your information, h_pid is the ID number of individuals and fb_age is the age at first childbirth and nchild is the number of children that the individual has.

When I just do 'sum or tab fb_age, detail', I realised that stata displays the result counting every observations of h_pid.

Thank you for your help.

* Example generated by -dataex-. For more info, type help dataex
clear
input long h_pid float(fb_age nchild)
 502 34 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
 602 40 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1001 22 1
1204 32 1
1204 32 1
1204 32 1
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
1502 29 2
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2501 30 1
2603 27 1
2603 27 1
2603 27 1
2603 27 1
2702 27 2
2702 27 2
3102 28 2
3102 28 2
3102 28 2
3102 28 2
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4202 29 3
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
4502 31 1
end

[Ken Chui]

Try egen tag():

egen unique = tag(h_pid)
sum fb_age if unique == 1