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

Stacked bar of year and the number of year colored by Theme, and sort from low to high by the y-axis.
SELECT Year, COUNT(Year) FROM exhibition GROUP BY Theme ORDER BY COUNT(Year)
SELECT "Year", COUNT("Year") FROM "exhibition" GROUP BY "Theme" ORDER BY COUNT("Year")