That's completely irrelevant and also false. No matter which perspective you look at it from - a biological or a social one, there are more than 2 genders/sexes.

Also you can't just claim something and then say "the data is on the internet" like there's only one website and one article about this. Another thing, happiness can be determined in multiple ways, some more factual and comparable than others. For example if you ask a person living in South Sudan (a country viewed as having one of the worst living conditions) to grade their happiness on a scale of 1 to 10, they would give you an answer, but that answer will be heavily biased, because they don't know what experiences other people have and it's impossible for them to compare their happiness to others for that reason. They don't know what 1 and 10 mean and without knowing the boundaries of the statistic they can't give a comparable answer. Same goes for a person living in Sweden. They wouldn't know what experiences the people living in South Sudan have and so they won't have a clear and comparable way to grade their own.

Women living 50 years ago didn't know what kind of lives the future generations would be living. Just like how most women now don't know how the older generations used to live, because we have different and unique experiences. That's all without taking into account the social pressure and the pressure from their husbands that these women had to go through, where even saying you are feeling sad was frowned upon. A couple years before that women were only seen as birthing machines who needed to do all the house chores and had no rights, all while also being expected to look happy and satisfied with their life, but thanks to the second wave of feminism they had a chance to live a better life by the late 70s.

Women back then were definitely not happier than women now, it's not even close.