How to calculate mean values per values in other column in one PROC SQL query in SAS Enterprise Guide?

I have query in PROC SQL with result as table in SAS Enterprise Guide like below:

My query:

proc sql;
create table work.my_table as 
select 
ID
, COUNTRY
, VALUE
from library1.table1
;quit;

Result of query in PROC SQL:

ID  | COUNTRY   | VALUE
----|-----------|---------
111 | FRANCE    | 1
222 | GERMANY   | 3
333 | FRAMNCE   | 2
444 | FRAMCE    | 3
555 | GERMANY   | 5

My task:

I need to modify my query, so as to have one more column: "MEAN_1" where will be mean of value (columns: "VALUE") per country (column: "COUNTRY")

Desire output:

ID  | COUNTRY   | VALUE   | MEAN_1
----|-----------|---------|-------
111 | FRANCE    | 1       | 2
222 | GERMANY   | 4       | 4.5
333 | FRAMNCE   | 2       | 2
444 | FRAMCE    | 3       | 2
555 | GERMANY   | 5       | 4.5

Because:

• values for FRANCE are: 1, 2, 3 --> so mean will be (1+2+3) / 3 = 2
• values for GERMANY are: 4, 5 --> so mean will be (4+5) / 2 = 4.5

How can I modify my query in PROC SQL in SAS Enterprise Guide from the begining of my question, so as to have in result table like above in "Desire output" ?

The result of your query (input) does not match the expected output.

• Value for id=222 does not match
• France is misspelled twice

In other flavors of SQL, you would achieve this with a subquery and a join.
However using SAS SQL you don't have to as SAS it allows you to include other variables and remerges the data together automatically. More in-depth explanation can be found in this answer.

proc sql;
   create table want as
   select *,
          mean(value) as mean_value
   from have 
   group by country
   ;
quit;

Using a double DoW Loop

proc sort data=have; by country; run;

data want;
    do _n_ = 1 by 1 until (last.country);
        set have;
        by country;
        sum=sum(sum, value);
    end;

    mean_value=divide(sum, _n_);

    do until (last.country);
        set have;
        by country;
        output;
    end;

    drop sum;
run;

Both hold the same result

id  country value mean_value
111 FRANCE    1       2
222 GERMANY   4      4.5
333 FRANCE    2       2
444 FRANCE    3       2
555 GERMANY   5      4.5