Actual jury verdicts are a matter of public record maintained by the clerk of the court for each respective court. This tells someone the final verdict in the case and the nature of the case, but it would be much more cumbersome to obtain the full dialog between a jury and the court during deliberations, which would require someone to commission of transcript of that part of the official record of the case on a case by case basis.
There are private parties who study such things and collect data in connection with their research on a research project by research project basis. Mostly, these people are professors at universities or colleges, think tank fellows, and, in civil cases, commercial data collectors, especially a firm that operates under the trademark "Jury Verdict Reporter".
There is also a cottage industry of professional "jury consultants" who study these matters and share information with each other as well.
In criminal cases, both prosecutors and public defenders typically handle scores to hundreds of cases per year, the vast majority of which are before juries, so anyone who has experience in one of those positions for many years also has a quite accurate understanding of what juries tend to do in various situations.
Journalists who have covered a court beat, bailiffs, judges, and the courtroom clerks of trial judges, tend to acquire this knowledge, over years of experience.
Civil jury trials are vastly less common, so lawyers who have never had criminal practices rarely acquire this depth of knowledge about how juries behave from personal observation. The average lawyer conducts less than one civil jury trial per lifetime (although that is, in part, because many lawyers do not have civil trial practices). I have more jury trial experience than the average civil trial lawyer and have participated as a lawyer in fewer than ten of them in twenty years.