ปีที่แล้วมีคะแนนน้อยกว่า 16 คะแนนในคลาส 500cc คืออะไร?
What was the last year that they had less than 16 points in class 500cc?
df = pd.DataFrame(columns=['year', 'points', 'class'])
df[(df['points'] < 16) & (df['class'] == '500cc')].year.max()