| Year | Total Expenses | Average Net Price | 
|---|---|---|
| 2015 | $18,988 | $12,830 | 
| 2016 | $19,218 | $13,028 | 
| 2017 | $19,631 | $12,897 | 
| 2018 | $19,631 | $12,375 | 
| 2019 | $21,290 | $13,230 | 
| 2020 | $21,321 | $13,261 | 
| 2021* | $21,579 | $13,292 | 
| 2022* | $21,840 | $13,322 | 
| 2023* | $22,104 | $13,353 | 
| 2024* | $22,372 | $13,383 | 
| 2025* | $22,643 | $13,414 |