This is mainly because the negative contribution of mobile phone charges increased with the base year of the CPI being changed from 2015 to 2020.
However, the year-on-year rate of change in the CPI that excludes the effects of temporary factors such as mobile phone charges and energy prices has been slightly positive even with the new base year of 2020, although this is an estimate. The right panel of Chart 10 shows developments in the indicators for capturing the underlying trend in the CPI.