7 Property operating expenses
| | 2018 | 2017 |
Taxes | 1,980 | 1,663 |
Insurance | 182 | 205 |
Maintenance | 4,534 | 6,971 |
Valuation fees | 73 | 113 |
Property management fees | 1,083 | 1,046 |
Letting and lease renewal fees | 2,755 | 2,731 |
Other operating expenses | 4,459 | 4,596 |
Addition to provision for bad debts | (26) | (288) |
Total property operating expenses | 15,040 | 17,037 |
In 2018, € 0.1 million (2017: € 0.2 million) of the maintenance expenses related to unlet properties.