Year Percent change (Units) 2013 2.605 2014 3.027 2015 3.223 2016 2.388 2017 1.166 2018 0.443 2019 1.412 2020 2.959 2021 4.227 2022 3.244 2023 3.378 2024 3.264 2025 2.564 2026 2.267 2027 1.988 2028 1.802 2029 1.721