When did the scoring of the ACT change?

The scoring of the ACT underwent significant changes in 2015. Before that, the ACT was scored on a scale of 1 to 36 for each section and an overall composite score, but the 2015 updates introduced a new scoring system for the optional Writing section, with scores ranging from 2 to 12. Additionally, the ACT began using a more detailed set of sub-scores and a STEM score to provide insight into students' performance in specific areas.