From 1st quarter 1998, the municipal indices of earnings were based on new data extracts from the public pay transfer systems, which were adjusted in relation to earlier data reports. As a consequence of this, there was a break in the indices of earnings between 1997 and 1998. The data break implies that the indices from 1998 onwards are overstated by approximately 1.5 pct. However, the rates of increase are comparable throughout the entire period.