Passage: John Graunt noted that in London over a 35-year period in the 17th century (1628–62), the birth sex ratio was 1.07; while Koreas historical records suggest a birth sex ratio of 1.13, based on 5 million births, in 1920s over a 10-year period. Other historical records from Asia too support James hypothesis. For example, Jiang et al. claim that the birth sex ratio in China was 116–121 over a 100-year period in the late 18th and early 19th centuries; in the 120–123 range in the early 20th century; falling to 112 in the 1930s.
Did the birth sex ratio in China have a wider range in the 18th and 19th centuries or the early 20th century? During which century was the birth sex ratio the highest in China? How many points did London's birth sex ratio differ from Korea's? Was the birth sex rate for China higher in the 18th century or the 1930s? Was the birth sex ratio higher in 1628 or the 1920s? Which researchers are named that studied the Asian birth sex ratio in either Korea or China?