It's percentage of the entire population, if you organized everyone from lowest to highest IQ, what percentage of the entire population would you need to include for them to be in the top. It's a little clearer when a point of interest is near the top. E.G. "person is in the top 1% of people in terms of wealth."
A less kind way to say it is '91% of people have a higher IQ than this person'.
Which of these candidates do you think will be more willing to have their minds changed with protests and petitions?
Nothing is going to be easy or perfect, but we can at least choose the most likely candidate that is slightly more aligned with our desired outcome and then fight for what is needed.