CREATE TABLE exhibition_record (Exhibition_ID NUMBER, Date CLOB, Attendance NUMBER)
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)

Find those themes and years for all exhibitions with ticket prices lower than 15, group by themes, count year, and the x-axis is Year, show y-axis in descending order.
SELECT Year, COUNT(Year) FROM exhibition WHERE Ticket_Price < 15 GROUP BY Theme ORDER BY COUNT(Year) DESC
SELECT "Year", COUNT("Year") FROM "exhibition" WHERE "Ticket_Price" < 15 GROUP BY "Theme" ORDER BY COUNT("Year") DESC