What's the sum of the number of episodes that originally aired after 1991 with a series number smaller than 21 and a DVD Region 2 release date of 26 march 2012?
CREATE TABLE table_45281 (
    "Series Number" real,
    "Number of Episodes" real,
    "Original Air Date" real,
    "DVD Region 2 release date" text,
    "DVD Region 1 release date" text
)
SELECT SUM("Number of Episodes") FROM table_45281 WHERE "Original Air Date" > '1991' AND "Series Number" < '21' AND "DVD Region 2 release date" = '26 march 2012'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What's the sum of the number of episodes that originally aired after 1991 with a series number smaller than 21 and a DVD Region 2 release date of 26 march 2012? ### Input: CREATE TABLE table_45281 (
    "Series Number" real,
    "Number of Episodes" real,
    "Original Air Date" real,
    "DVD Region 2 release date" text,
    "DVD Region 1 release date" text
) ### Response: SELECT SUM("Number of Episodes") FROM table_45281 WHERE "Original Air Date" > '1991' AND "Series Number" < '21' AND "DVD Region 2 release date" = '26 march 2012'