Game concept
Development Growth
From the game's encyclopedia
Development Growth measures how far along the County is towards increasing its Development.
At 100 Development Growth, the Development increases by 1.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Development Growth is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Development Growth measures how far along the County is towards increasing its Development." Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.