Join Date:Joined: Jul 2013
If this is important to you for some reason, ask your carrier i.e. phone tech support or open a support ticket. It's easier to look at a firmware repository such as sammobile, but they don't always have the latest firmware for all carriers. And different carriers roll out updates on varying schedules, so there is no universal answer.
A Google search would quickly tell you what the latest firmware period is. But not necessarily if that update is available from your carrier.