The availability of public logs for CQ WW CW and SSB contests spanning thirteen years (cq-ww-2005--2017-augmented.xz; see here for details of the augmented format) allows us to look at the variation in the rate at which DX QSOs are made throughout each contest over a relatively long period. (I here define DX QSOs as those between different zones; other definitions are obviously possible.)
This exercise is essentially identical to the one performed last year for the twelve years of data then available.
In the plots, the number of QSOs is accumulated every ten minutes, so there are six points per hour.
I present the results without comment.
In regard to the 10m results, I should point out, as I did last year, that the CW contest occurs roughly a month after the SSB one, and is therefore considerably closer to the winter solstice, with the concomitant decrease in the number of hours of common daylight between Europe and North America (particularly western NA). I have long wondered what would happen if CQ WW (and CQ WPX and ARRL DX) would switch CW and SSB weekends every year.