Reza Shah Pahlavi, who abdicated in 1941, was succeeded by his son, Mohammad Reza Shah Pahlavi (r. 1941–79). No fundamental change occurred in the economy of Iran during World War II (1939–45) and the years immediately following. However, between 1954 and 1960 a rapid increase in oil revenues and sustained foreign aid led to greater investment and fast-paced economic growth, primarily in the government sector. Subsequently, inflation increased, the value of the national currency (the rial) depreciated, and a foreign-trade deficit developed. Economic policies implemented to combat these problems led to declines in the rates of nominal economic growth and per capita income by 1961.