Hong Kong’s jobless rate remained unchanged at 6.1 per cent in August during the height of the city’s third wave of Covid-19 infections, but the number of people underemployed hit a 17-year high.For the rolling three months between June and August, the unemployment rate remained the same as for between May and July, the Census and Statistics Department revealed on Thursday, with the number of people without work rising by 5,800 to 248,300.The third wave of the Covid-19 pandemic in early July…