However, the May CPI rose 1.4 % on-year, the office said.
Three of the 11 groups of goods and services used to calculate the CPI saw month-on-month price declines. The transport group saw the strongest fall of 2.29 %, followed by food and catering services with 0.41 % and housing, electricity, water, fuel and building materials with 0.97 %.
The groups of garment-headgear-footwear and education saw no fluctuations during the period, while all other groups recorded price increases.
In the first five months of 2020, the municipal average CPI increased 3.76 % annually.