st: Store cross-section means of stacked data

["Jonas Dovern" <J.Dovern@student.unimaas.nl>]

Dear Stata-Users,

I have the following problem with regard to efficient programming/data 
storing:

Assume I have a data in stacked form, e.g.:

Country    Year    Var1
A    1    q
A    2    w
A    3    e
A    4    r
A    5    t
B    1    z
B    2    u
B    3    i
B    4    o
.    .    .
.    .    .
.    .    .
C    5    p

What I want is to compute the average across countries of Var1 for each 
year - and store these values to make a plot later on. So far I created a 
new variable, say Mean, and filled it with the mean values. The new 
variable, however, is also of size #Counties*#Years repeating the entries 
for each year #Countries-times -- although I would need to store the mean 
for each year only once.

What is the usual way to perform this task? Store the values in a matrix? 
Can I easily plot this matrix later on?

Thanks for your help,

Jonas

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