(Preface by stating that I am no historian, but this topic falls into the scope of a period that I take a lot of interest, I have a few history books with reference if mods need them)

350 years ago, that would be in 1664.

Context

The Tokugawa shogunate has stabilized the country after a few decades of local and not so local wars, the seclusion policies are in place. In the previous century, Hideyoshi has started to confiscate weapons in the countryside. You have to keep in mind that in a stabilized country with not much fighting going around, you do not need many warriors.

At that time, there is indeed a "warrior class" (Bushi), different from the commoners (Hyakkusho) and the "townspeople" (machinin). Although there is some limited fluidity between social classes, the society is overall quite static (you are born a lower class, tough shit...). The warriors are then divided in several other classes (allowed or not to have an audience with the shogun, etc.).

What you probably refer to is this warrior class.

It so happens that 1664 is just a few years after the Keian Rebellion, which scared the shogunate enough to put in place several policies to limit the "ronin" problem. In 1663, the shogun enacted a new sets of Military rules (Buke Shohatto), and this particular set of rules included a rule forcing to seek a new lord if the previous lord died (rather than commit suicide). The shogunate also soften the rule forbidding the adoption of warriors as the successor of the family (in case there was no heir). And finally, the shogunate put efforts to have ronin get proper jobs.

This means that overall, even if someone was socially casted as a "warrior", roaming around with your sword killing people was not the thing to do, and was frowned upon by the shogunate and could put you in trouble.

To come back to your question, the closest I have is a source dating from 1622, which is not very far from the date you mention. It's an estimation of the composition of the various classes for the Domain of Kokura, giving 5,3% of warriors (and unsurprisingly an overwhelming majority of commoners)

I also have another source for late Edo period. It's more than 200 years after your date, but as I was mentioning the social classes were stable so it will give a very rough estimate. It is for a different domain, and gives 9% of warriors.