https://www.opensecrets.org/elections-overview/donor-demographics

https://www.nptrust.org/philanthropic-resources/charitable-giving-statistics/

12 political megadonors are responsible for $1 of every $13 in federal elections since Citizens United and 25% of all giving from the top 100 ZIP codes — a total of $3.4 billion

https://issueone.org/articles/outsized-influence-12-political-megadonors-are-responsible-for-1-of-every-13-in-federal-elections-since-citizens-united-and-25-of-all-giving-from-the-top-100-zip-codes-a-total-of-3-4-bil/