You can toss any hope or comparison of passenger numbers for 2020 out the window with the impact of coronavirus.
DL TPAC flights to PVG, PEK suspended. ICN reductions. Potential for more near-term reductions, many companies putting a freeze in for international travel in the near term, and economic concerns.
This isn't just a DTW things, its everyone.

Air travel rises and falls with the economy, and of course black swan events like 9/11 and irrational fear of pandemics.