| Year | Total Expenses | Average Net Price | 
|---|---|---|
| 2015 | $19,412 | $12,684 | 
| 2016 | $19,926 | $12,971 | 
| 2017 | $21,290 | $14,326 | 
| 2018 | $21,290 | $13,833 | 
| 2019 | $23,847 | $15,438 | 
| 2020 | $24,359 | $15,950 | 
| 2021* | $25,005 | $16,480 | 
| 2022* | $25,667 | $17,027 | 
| 2023* | $26,347 | $17,592 | 
| 2024* | $27,046 | $18,176 | 
| 2025* | $27,762 | $18,779 |