| Year | Total Expenses | Average Net Price | 
|---|---|---|
| 2015 | $17,970 | $15,110 | 
| 2016 | $17,330 | $14,421 | 
| 2017 | $17,386 | $14,466 | 
| 2018 | $17,386 | $14,411 | 
| 2019 | $17,684 | $14,352 | 
| 2020 | $17,902 | $14,570 | 
| 2021* | $17,959 | $14,515 | 
| 2022* | $18,017 | $14,459 | 
| 2023* | $18,074 | $14,405 | 
| 2024* | $18,132 | $14,350 | 
| 2025* | $18,190 | $14,295 |