 How many companies in each headquarter? Plot a bar chart.
CREATE TABLE station_company (
    Station_ID int,
    Company_ID int,
    Rank_of_the_Year int
)

CREATE TABLE gas_station (
    Station_ID int,
    Open_Year int,
    Location text,
    Manager_Name text,
    Vice_Manager_Name text,
    Representative_Name text
)

CREATE TABLE company (
    Company_ID int,
    Rank int,
    Company text,
    Headquarters text,
    Main_Industry text,
    Sales_billion real,
    Profits_billion real,
    Assets_billion real,
    Market_Value real
)
SELECT Headquarters, COUNT(Headquarters) FROM company GROUP BY Headquarters