Oman relied upon its income mainly from its oil reserves which were not large compared with those of her neighbours to the north in Saudi, the Gulf States and Iran.
Production of oil was still relatively low and very little LNG was exported. There had also been precious little rise in the price of crude oil for many years. That was about to change but this was not apparent in 1972.
The blue line on the graph shows the nominal oil price and the yellow the $(2008) price.