V.69: 3,147,224
V.70: 3,039,487
V.71 : 2,890,263
DROP
V.85: 2,400,524
V.84: 2,393,553
V.83: 2,435,076
DROP
V.92: 1,776,868
In less than 20 volumes this series has lost between 700,000 to 800,000 readers.
One can notice a steady drop over the years, as the interest in One Piece fades for each new arc.
One Piece sales per year:
>2010
32,343,809
>2011
37,996,373
>2017
11,495,532
>2018
8,113,317
Between 2011 and 2018, One Piece has lost 29,000,000 yearly sales. This is the biggest flop in the history of manga. No other manga has lost this many sales in such a short amount of time.
Now, let us compare the other series with One Piece and they are doing over a prolonged period of time.
This was calculated over a few years.
>One Piece - 5,969,851 ---> 3,110,049
>Haikyu!! - 3,086,097 ---> 2,523,071
>My Hero Academia - 2,097,088 ---> 2,516,768
>Black Clover - 790,032 ---> 2,033,277
OP lost nearly 3M sales, while BC and MHA sold more and HQ lost 400k. With this we can conclude that One Piece is dying and nobody likes Wano.