Looking at historical rates of suicide is really hard because it was still a crime in many places, and there was strong social convention to not name something as suicide unless the evidence was overwhelming.
In England the law changed in 1961, but coroners still had to use "beyond all reasonable doubt" to come to a conclusion of suicide until 2018. There was a case (Maughan) that changed the burden of proof to "balance of probabilities".
In the US you have the added complexity of different laws for each state, with different standards that coroners work to. Getting coroners to work to common standards is notoriously difficult.
In England the law changed in 1961, but coroners still had to use "beyond all reasonable doubt" to come to a conclusion of suicide until 2018. There was a case (Maughan) that changed the burden of proof to "balance of probabilities".
https://www.bailii.org/ew/cases/EWCA/Civ/2019/809.html
https://www.bailii.org/ew/cases/EWHC/Admin/2018/1955.html
In the US you have the added complexity of different laws for each state, with different standards that coroners work to. Getting coroners to work to common standards is notoriously difficult.