I noticed this was created in 1989. Do you know the statistic for today?
The Guerrilla Girls do actually go to the Met and recount and recollect this statistic regularly.
The most recent version of this poster that they produced is from 2012. At that time, it read "Less than 4% of the artists in the Modern Art sections are women, but 76% of the nudes are female."
They have also created versions of this poster for other museums, most recently the Museu de Arte de São Paulo, in 2017.