| (24) | Operating leases |
| | | 2017 | | 2016 | | 2015 | | |||
| Lease expenses | | $ | 416,437 | | | 403,116 | | | 359,749 | |
| 2018 | | $ | 184,253 | |
| 2019 | | | 140,420 | |
| 2020 | | | 120,365 | |
| 2021 | | | 103,316 | |
| 2022 | | | 120,031 | |