HONG KONG, Aug 15 (Reuters) - China's fertility rate is estimated to have dropped to a record low of 1.09 in 2022, the National Business Daily said on Tuesday, a figure likely to rattle authorities as they try to boost the country's declining number of new births. The state-backed Daily said the figure from China's Population and Development Research Center put it as having the lowest fertility level among countries with a population of more than 100 million. China's fertility rate is already one of the world's lowest alongside South Korea, Taiwan, Hong Kong and Singapore. Concerned about China's first...