Inflation in December has declined to 6.16 per cent from 7.52 per cent in November. The reading for October headline inflation was revised to 7.24 per cent from 7 per cent.Food prices rose 13.68 per cent year-on-year last month, much slower than an annual rise of 19.93 per cent in November. Cooling in food prices slowed down retail inflation to a three-month low of 9.87 percent in December.