3 Feb 1991 to 1992/94(?)
US foreign surface letter rate 70 c (3 Feb 1991-8 Jul 1995)
Swedish standard total fee for incoming due items: 600 öre (2 Jan 1991-1992/94(?)
US handstamp shows amount missing in US cents and US surface letter rate.
In Sweden the indicated fraction was ingnored and instead a standard fee of 600 öre was charged normally paid by affixing stamps on an advice card sent along with item by the Swedish post office. Items handed out at the window or by rural carriers may have the amount due affixed on the item.

Double rate air mail letter with 50 c