What are the sales figures these days compared to, say, ten or twenty years ago?
Latest comparable figures I have is for September 2021.
In September 2021, issue #779 of the monthly WW title sold an est. 30,000 units, with another 18,000 units sold for issue #4 of the miniseries "Wonder Woman: Black & Gold", as well as 17,000 units of issue #7 of "Sensational Wonder Woman". Combined, 65,000 units of new Wonder Woman comics were sold.
In September 2011, issue #1 of the monthly WW title sold 76,214 units. Of course, this was the launch of the New52, and there was a special hype surrounding all DC titles that month. For context, the preceding month of
August 2011 had issue #614 of WW sell 29,223 units, with another 29,492 units sold for #3 of the event tie-in miniseries "Flashpoint: Wonder Woman & the Furies", as well as 10,079 units of the one-shot "DC Retroactive: Wonder Woman in the 80s" and 9,290 units of "DC Retroactive: Wonder Woman in the 90s". Combined, 78084 units of new Wonder Woman comics were sold in August '11, though comparing those numbers among themselves, it appears to me the Flashpoint event tie-in factored heavily into the sales of WW & the Furies.
In September 2001, "Wonder Woman" #174 sold 32,221 units, being the sole WW title of the month.
So, compared to ten years ago, the regular Wonder Woman title sells about the same, considering the hype and high sales of the early New52 issues as an extraordinary event, while the character does not need to rely on event tie-ins to sell more units of miniseries. Considering that digital sales are not included, the regular WW title is selling at least as good as twenty years ago, while the character apparently not being popular enough to sell miniseries or oneshot titles.