Annually on 1 July, the rent will be indexed based on the change of the monthly price index figure according to the consumer price index (CPI) series all households (2015=100), published by Statistics Netherlands (CBS). The modified rent is calculated according to the formula: the modified rent is equal to the current rent on the modification date, multiplied by the index figure of the calendar month lying four calendar months before the calendar month in which the rent is modified, divided by the index figure of the calendar month lying sixteen calendar months before the calendar month in which the rent is modified.