CREATE TABLE artist (Artist_ID NUMBER, Name CLOB, Country CLOB, Year_Join NUMBER, Age NUMBER)
CREATE TABLE exhibition (Exhibition_ID NUMBER, Year NUMBER, Theme CLOB, Artist_ID NUMBER, Ticket_Price FLOAT)
CREATE TABLE exhibition_record (Exhibition_ID NUMBER, Date CLOB, Attendance NUMBER)

Group by the theme and count the year with a stacked bar chart.
SELECT Year, COUNT(Year) FROM exhibition GROUP BY Theme
SELECT "Year", COUNT("Year") FROM "exhibition" GROUP BY "Theme"