European Central Bank:

The primary objective of the European Central Bank, as laid down in Article 127(1) of the Treaty on the Functioning of the European Union, is to maintain price stability within the Eurozone. The Governing Council in October 1998 defined price stability as inflation of under 2%, “a year-on-year increase in the Harmonised Index of Consumer Prices (HICP) for the euro area of below 2%” and added that price stability ”was to be maintained over the medium term”. (Harmonised Index of Consumer Prices) Unlike for example the United States Federal Reserve Bank, the ECB has only one primary objective but this objective has never been defined in statutory law, and the HICP target can be termed ad-hoc.

Please answer a question about this article. If the question is unanswerable, say "unanswerable". What did the Harmonised Index of Consumer Prices state that price stability had to be decreased from?
unanswerable