As part of the constant refinement of the TTCI, indicators that are no longer being published, have been replaced by the source, or have had a significant change in methodology have been swapped out. Moreover, please note that even for indicators that have not been replaced, source data revisions can occur. Therefore, while efforts were made to keep TTCI results comparable from one edition to the next, refinement in indicators and data revisions could cause shifts in ranking and scores that are not due to actual performance.