2017 0.14 0.24 0.11 0.05 0.15 2018 0.13 0.26 0.00 0.17 0.10 2019 0.19 0.27 0.46 0.11 0.12 2020 0.16 0.17 0.00 0.12 0.18 Because contractors not directly supervised by Alcoa maintain their own health and safety programs and are accountable for investigating incidents involving their employees, certain details associated with their internal investigations are not fully transparent to Alcoa.