I'd prefer the graph starting at zero on the Y axis.
Plus the number drops extremely sharply between 1935 and 1940 from around 53 thousand to 23 thousand. Playing devil's advocate, the JWs could argue that many partakers in 1935 later "realised" they were other sheep. So only around 25,000 or so should be counted from this period. That would still leave room for modern anointed, first century anointed, and a trickle in between, as has long been the teaching. Add in a percentage who are wrong or leave JWs and they could still string this out for a long time. Basically until the number partaking itself reaches near 144,000 they'll probably still argue it all makes sense.
The fact the it's increasing when it should be decreasing is a bigger problem that the overall number. They could abandon the teaching, stop publishing the number, or call most partakers liars or crazy. So far they seem to be going with the crazy option and burying their heads in the sand.