Reminder that Haikyuu is most likely higher than this. To get 0.88, you used the 42 volumes and the 37m number we got recently. However Haikyuu has to be over 37m. If we trust Oricon:
It started in 2012, but did not reach the yearly top 30
2013: 2,056,211
2014: 8,283,709 (Total: >10,339,920)
2015: 6,531,508 (Total: >16,871,428)
2016: 5,474,394 (Total: >22,345,822)
2017: 5,067,939 (Total: >27,413,761)
2018: 5,030,624 (Total: >32,444,385)
2019: 4,514,838 (Total: >36,959,223)
That's 37m units sold (not shipped) as of mid-november 2019, without its 2012 sales (hard to say, over 500k maybe?) and its 2020 sales (around 1.8m as of this week). Considering shipments are always higher than sold-through data (and those numbers are supposed to include shipment, since they usually get updated when a new volume releases, with its first print included), it's safe to say that Haikyuu's rate is closer to 1 than this