Billionaire Robert Ng Chee Siong said his hotels saw their occupancy rates fall to as low as a third as Hong Kong’s hotel industry was hit by a huge drop in tourist arrivals amid the outbreak of Covid-19.Average occupancy rates at the tycoon’s Sino Hotels (Holdings), which operates three hotels in the city including the Conrad Hong Kong in Admiralty, dropped to as little as 34 per cent as the pandemic crippled international travel. Average room rates plunged by 43 per cent in the year ended…