You keep implying that the number of women and or the percentage of women in computer fields dropped, yet everything you seem to quote as evidence simply says there was a an uptick in men persuing IT related jobs during the dotcom boom. Can you provide any evidence that actually supports your position that there was a mass exodus, or do you simply not understand how ratios work?
First, the ratio's are prima facia evidence of gender bias.
Second, the original data can be found at this
link, so you can knock yourself out to investigate rather than hand-waving. The data show that the rate of expansion is broadly similar between men and women, as judged by % change in the undergraduate degrees awarded in a given year compared to the previous year. However, in terms of absolute numbers, this means that when the field expands (as judged by an increase in all computer science undergraduate degrees), the proportion of women decreases since the baseline number of men is higher (just thought I'd explain that property of ratios to you). If this continues, the growth in the number of male degrees will so far outstrip any growth in absolute female degree numbers, the proportion of women getting undergraduate computer science undergraduate degrees will approach 0%. The field is caught in an self-reinforcing cycle that is squeezing women out. That's just simple mathematics. I hope you understand. At a social science level, this pattern arises when people in a field prefer to work with people like them, in this case, men preferring to work with men.
Third, in 1982-1983, 15,641 men received undergraduate computer science degrees and by 2011 this number had grown to 38,773. The comparable numbers for women are 8,924 for 1982-1983 and 8,611 in 2011-2012. Perhaps not the large scale exodus that for which you requested evidence, but it does indicate that growth in undergraduate computer science degrees has stagnated for women while things have been charging ahead for men. I wonder why.
Fourth, there were some years in which the numbers of undergraduate degrees were lower than the previous year as the field contracted, presumably due to economic downturns. Three years in the database exhibited a yearly reduction of male undergraduate degrees by 10% (the three worst years for males). The corresponding reduction for women are 19%, 16%, and 18%. Thus, there is a tendency for disproportionately greater reduction in degrees for women when the field contracts.
So... you think this is a perfect picture of gender equality in a field or what?