Like Finn said, manufacturers report their numbers to the Association of Equipment Manufacturers. In turn the members get a summary - so the manufacturers know total and their share but not the distribution of the others. Here is the November 2021 report. Next analysts crunch the numbers different ways like tracking shipments, import records for machines and engines, etc. when I worked for Allis-Chalmers/Deutz-Allis, our marketing department told us percentage market share. Then I moved to CaseIH where a lot more effort was put into market research and our marketing department knew every individual sale made (larger equipment). Then on to Caterpillar where construction industry reported every machine built and shipped. I have read industry analyst reports that in the CUT and SCUT categories, Kubota leads by far with Deere the only somewhat close competitor. Total sales of all the rest don’t match the total of either Deere or Kubota. Whether the analysts are right I don’t know, but finding the info is their only job. Note the numbers and the large sales increase from 2020 to 2021. You might think that with COVID, 2020 was a slow sales year. That’s not the case. 2020 was higher than 2019 in all but one category - self-propelled combines. Analysts believed it was because people had more free time to use equipment and those working also got stimulus money and spent it on foolishness like tractors. So today’s shortage? How could manufacturers forecast these large sales jumps? Not my thought - repeating industry analyst’s statements.