Average Paperback Prices, 2016-19
| Genre | 2016 | 2017 | 2018 | 2019 |
|---|---|---|---|---|
| Young adult | $25.49 | $18.40 | $18.02 | $18.40 |
| Mathematics | $97.31 | $78.54 | $106.69 | $76.99 |
| Comics and graphic novels | $18.60 | $18.49 | $19.12 | $20.60 |
| Reference | $156.03 | $189.53 | $186.25 | $148.88 |
An intern at a publishing house who is writing a report is asked to determine which of several genres of books published in 2019 had paperbacks with the lowest average price. Consulting the table, she determines that, on average, the least expensive paperbacks in that year belonged to the genre of __________