CREATE TABLE table_name_15 (year INT, issue_price VARCHAR, mintage VARCHAR)

What is the Year of the Coin with an Issue Price of $1089.95 and Mintage less than 900?
SELECT SUM(year) FROM table_name_15 WHERE issue_price = "$1089.95" AND mintage < 900
SELECT SUM("year") FROM "table_name_15" WHERE "$1089.95" = "issue_price" AND "mintage" < 900