It is a sales development timeline recording the annual sales volume trend from 2015 to 2019. In 2015, the number of products sold was 2471. In 2016, the sales volume fell. The number of products sold was 1789. In 2018, the sales volume grew steadily. The number of products sold was 5863. In 2019, the number of products sold was 4985. With a timeline, the annual sales volume is presented clearly. Timelines can help people organize information in chronological order so that they can understand growth, changes, recurring events, causality, and key events of historical, social, and scientific significance.