Dear Stata users,

Suppose we have a household survey data. And we have ages of every family members (in each family only one member was chosen to be respondent) in this dataset. Now if we want to caculate the mean age of the population that was composed of all members. And I don't want to "destroy" structure of the dataset by using -stack- or something else. How can I get that? The supposed data is like follows:

Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input float(age1 age2 age3 age4)
25 29  0  .
26 27  2  .
30 29  .  .
36 37  8  .
34 31  6  1
36 12  9  .
41 43 15  4
34 41  9  .
30 36 10  2
37 42 13  3
43 43 19  .
35 37  9  .
37 36  3  .
41 43 16  5
38 35  8  .
41 37 11  .
34 38  8  0
45 45 25 21
46 47 26 22
38 38 14  .
end