Before revision:  The mobility index calculation used in this study, has a worldwide extent and is based on the computation of cumulative navigated miles (CNM ) of all ships reporting their position and navigational status via AIS . We compare 2020 mobility levels to those of previous years assuming that an unchanged growth rate would have been achieved, if not for COVID-19.
After revision:  The mobility index calculation used in this study, has a worldwide extent and is based on the computation of : CNM of all ships reporting their position and navigational status via AIS . We compare 2020 mobility levels to those of previous years assuming that an unchanged growth rate would have been achieved, if not for COVID-19.