<human>:  I have a question about the Economic development of Ningde. When did the city become a city?
<bot>: Ningde was founded in 1921. It was originally a county in Fujian Province, China. In the late 1940s, it was promoted to a prefecture-level city. In the late 1950s, it was promoted to a municipality. In the late 1980s, it was promoted to a city.