When I went to university 20 years ago, there was precisely one woman in the lectures for the CS department, so less than 1%. The maths side, which I was also studying, had something approaching a 40% ratio.
After 20 years in IT working for schools, I have worked under precisely one woman (in a technical sense, not in a "they were the headmistress of the whole company"), who was an outlier and had been in banking IT for decades before and was nearing retirement. All the applicants for her replacement were male. Every time I've put out job ads (and HR are scrupulous about being equal-opportunity), from apprentices up, every single applicant was male. Every IT department I've visited has entirely male staff. We have employed women briefly, but in the "anyone can carry a computer" tier of jobs... not through want of trying, but we just don't get the applications from female applicants. Schools I've worked in have been majority-female staff in general. It just doesn't feed down to IT.
I refuse to let my department become toxic masculinity personified, so we are often the haven of staff, male and female alike, when they want some sanity. But I don't get any female applicants responding to widely-published, heavily-advertised, neutral descriptions of a job that involves nothing gender-specific, even in a female-heavy workplace. Yet we have female staff in finance doing high-level Excel and SQL, and I've worked with female teachers more than capable of teaching coding (some of them ex-COBOL programmers), and there's literally nothing in the job that's female-offputting.
There is obviously some disconnect somewhere - at some level women are discouraged from a career in IT or CS. And short of saying "female applicants welcome" or something (which is going to be construed as sexism or "looking for totty only"), as someone who hires IT staff, I can't do much more.
Helpdesk roles are perfectly well gender-neutral... anyone can man a helpdesk. Anyone can follow a procedural sheet. You don't even need to be in an office, helpdesks often operate remotely. I do speak to a number of helpdesks throughout the working day, but generally it's male. I hate to say it, but the female staff tend to be in the minority, not stretch past first-level support at all, or are literally "secretarial" staff who were answering the phone and just recording details for the IT people (almost exclusively male) to follow up on later, just so that the phone isn't ringing for too long.
I've met more female IT trainers than any other sub-profession. The techy staff, and especially the most-techy staff, tend to be male. And I say that not from a position of ignorance - I worked under a female IT Manager who taught me more than anyone else I've ever worked under, and I've worked with female teachers who were ex-COBOL programmers and who could happily geek out with me for ages. But the fact is that they are really in the minority. Whether that's manning the phones at a print service company, or programming up apps, or building servers in datacentres. Technically, I know more transgender women in the profession than I know women (I'm sure someone will complain about my wording there somehow implying that they aren't women, etc., and I'm sure my transgender friends will tell them to shut up because "he's okay" and they know what I meant).
How we fix it, I don't know. Going into schools and telling them that IT is a career for women just reminds me of Sheldon from Big Bang on his school visit where he tried to encourage the class of girls to get into science. I can't see it having much of an impact.