1.5 years is low for a murder trial. I would suspect the average is somewhere between 2 and 5 years. A lot of the time, if the defendant knows they are cooked, then they are just holding out for a better plea deal.

I've personally met defendants on their ninth year awaiting trial, and during COVID a lot of jails were forced to publish their detainees lists, and I noted some who were over 11 years without a trial.