Hong Kong retail sales plunged 13.1 per cent year on year in August, as the coronavirus pandemic continued to batter the struggling sector, marking a 19th consecutive month of contraction.Consumer spending dropped to HK$25.6 billion (US$3.2 billion) last month, contributing to sales for the first eight months of the year falling 30 per cent from the same stretch in 2019, according to provisional figures released by the Census and Statistics Department on Wednesday.A government spokesman said…