What are the statistical results of frequency records of ancient meteorites?

In 1970s, a large number of local chronicles of Ming and Qing Dynasties were consulted, and hundreds of ancient meteorite records were obtained, which laid a foundation for statistical research. The first is frequency statistics; The average number of years of each meteorite fall is only 1 time after more than 500 years due to the loss of many records in Xia and Shang Dynasties. After the Ming and Qing Dynasties, it was frequently recorded and well preserved, with an average of every two years 1 time. It is not surprising that this situation can be imagined. Strangely, during the 500 years from Qin and Han Dynasties to Yuan Dynasty, the so-called developed Tang Dynasty recorded the least meteorites, with an average of 58 years 1 time, while the Han Dynasty recorded 23 years and the Song Dynasty recorded 1 8 years. I'm afraid this phenomenon cannot be explained by the loss of records. By counting the frequencies of 100, 50 and 5 years, we can see that there are obvious fluctuations. The Tang Dynasty was the longest low tide period from 688 to 896, and there was no meteorite record for more than 200 years. Some people think that this fluctuation is not easy to explain, but there may be two reasons that have to be mentioned. First, the meteorite landing has its objective laws, and second, people's scientific and technological level, social status, attention, population density and distribution. Statistics of meteorite landing density and population density distribution show that they are closely related.