Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE exhibition_record ( Exhibition_ID int, Date text, Attendance int )
TABLE: CREATE TABLE exhibition ( Exhibition_ID int, Year int, Theme text, Artist_ID int, Ticket_Price real )
TABLE: CREATE TABLE artist ( Artist_ID int, Name text, Country text, Year_Join int, Age int )

### Question ###
What are the average ages of artists by countries? Visualize the result with a histogram, and I want to display in asc by the total number.

### Accurate SQL ###

SELECT Country, AVG(Age) FROM artist GROUP BY Country ORDER BY AVG(Age)