Year Percent change (Units) 2013 2.800 2014 1.300 2015 0.292 2016 1.214 2017 6.091 2018 3.221 2019 3.130 2020 4.833 2021 5.667 2022 6.056 2023 6.601 2024 4.300 2025 3.700 2026 3.500 2027 3.300 2028 3.100 2029 2.600