Each row is a year and each cell one quarter's passengers against that year's average. The first quarter is the lowest in all but three of the years, and the third almost always the highest.
Conditions and method
The third quarter has the highest index in 31 of the 36 plotted years. The other years peak elsewhere: 2001 (Q2), 2006 (Q2), 2008 (Q2), 2020 (Q1) and 2021 (Q4). A year’s swing is its highest quarterly index minus its lowest, in index points. The widest are 2020 (169.1), 2021 (63.5) and 2022 (26.6). Since the pandemic years the swing has been 26.6 in 2022, 16.4 in 2023, 13.9 in 2024 and 14.1 in 2025, against 14.6 to 17.2 in 2015 to 2019. The 2025 swing uses the nowcast fourth quarter.
The 2025 Q4 cell is a nowcast, not a published count: the official passenger count for that quarter is incomplete, so the figure is estimated from airport security (TSA) checkpoint counts. The other cells of the 2025 row are published counts, and the 2025 annual mean that each of its cells is indexed to includes the estimate.
Data run through 2025.