7 Property operating expenses
| | 2015 | 2014 |
Taxes | 1,691 | 1,173 |
Insurance | 211 | 152 |
Maintenance | 3,640 | 3,118 |
Valuation fees | 102 | 67 |
Property management fees | 1,247 | 1,017 |
Letting and lease renewal fees | 2,603 | 1,151 |
Other operating expenses | 3,257 | 2,421 |
Addition to provision for bad debts | 312 | 8 |
Total property operating expenses | 13,063 | 9,107 |
In 2015, € 0.2 million (2014: € 0.2 million) of the maintenance expenses related to unlet properties.