Create a Plot chart with a month-over-month comparison of the values [Linux]

Great suggestion OleksandrB​ !

Just a quick add-on comment for anyone reading this:

For month-over-month comparisons it's more likely to use Line Chart or Column Chart.

Having said that it will be good to adjust the month_text column like this : 

CASE GetMonth([date])
    WHEN 1 THEN '01. January'
    WHEN 2 THEN '02. February'
    WHEN 3 THEN '03. March'
    WHEN 4 THEN '04. April'
    WHEN 5 THEN '05. May'
    WHEN 6 THEN '06. June'
    WHEN 7 THEN '07. July'
    WHEN 8 THEN '08. August'
    WHEN 9 THEN '09. September'
    WHEN 10 THEN '10. October'
    WHEN 11 THEN '11. November'
    WHEN 12 THEN '12. December'
    ELSE ''
END AS month_text

This will facilitate the above mentioned charts to display the months in chronological order!