Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
What year was the class 253 larger than 18 built?

### Inputs:
table_name: table, columns: ['Class', 'Operator', 'Number', 'Year Built', 'Cars per Set', 'Unit Numbers.']

### Response:
SELECT Year Built FROM table WHERE Class = class 253 AND Number > 18