The 1983 Ranger was the first year, but 1984 was the first year that FuelEconomy.gov lists.
It has dozens of variants!
The 2.8 L, v6, Automatic 3-speed was rated 13/15 and the 2.2 L, i4, Manual 4-speed [diesel] was rated 25/28, but that was the current rating.
I don't know what it was originally rated, nor the real-world mileage.
The second generation didn't come out until 1993, although there was a facelift in 1989.