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

### Instruction:
What is the earliest year with less than 45 points for Yamaha team in 21st rank?

### Inputs:
table_name: table, columns: ['Year', 'Class', 'Team', 'Points', 'Rank', 'Wins']

### Response:
SELECT MIN Year FROM table WHERE Points < 45 AND Team = yamaha AND Rank = 21st