The mainland's consumer price index rose 0.4 per cent in December last year compared with the same period a year earlier, an official with the State Statistical Bureau said yesterday. A good grain harvest amid stable demand had kept food prices low and the consumer price index (CPI) down. CPI, which is broader based than the retail price index, grew 1.1 per cent in November year on year. The index grew 2.8 per cent last year compared with the previous year.