I wonder if it's pre-built with those conditions or if it's because people with those conditions are going to be extra careful and objective in how they gather information because they're aware of their limitations.
Could also be a correlation due to people who actually get diagnosed with dyslexia/dysgraphia being more likely to live in places that are more affluent or with better mental healthcare.
That would tend to correlate with generally more accepting populations.
Looks like anyone can take this! But I guess that also means... did the dyslexics/dyscalculics self-select themselves?
Edit: took one. There is a demographics questionnaire where you can list whether you have disabilities, dyslexia is in there (but not Autism??)... So it is self-selected. And on unrelated note, I am apparently in the 1% that has a strong automatic preference for physically disabled rather than not-disabled people (facepalm