In the 12 month period ending March 2009, the RPI (Retail price index, a measure of inflation in the UK based on the change in cost of a basket of goods) went negative for the first time since 1960, showing an overall reduction of cost over the period of 0.4%. This peaked in the 12 month period ending June 2009 showing an RPI of -1.4%, the lowest since records began in 1948.