Between April 1990 and November 2009, the annual growth rate is derived from official monthly variations between April 1989 and November 2009. (Spliced series). For December 2009, annual rates from CPI basket December 2008=100, are used. From January 2010 to December 2013, annual rates from CPI basket 2009=100, are used. From January 2014 to December 2018, annual rates from CPI basket 2013=100, are used. Finally, since January 2019, the current year-over-year growth rates 2018=100, are used.
Headline CPI for the period 2010 to date, uses the official series from INE (base 2018=100). For the previous periods, it is spliced with the official monthly inflations from INE.