100% of the African-American population took part in the Civil Rights Movement.
Then, as now; there are no neutral positions, or as Howard Zinn put it, “you can’t be neutral on a speeding train.”
Your question is very broad; I think what you want to know is; what percentage made a positive contribution to the CRM, or what percentage were actively supporting or contributing to the CRM; then your answer will vary according to region.
In some areas, there was overwhelming support and active participation, like during theMontgomery Bus Boycott. Other campaigns or efforts didn’t have majority support but still attracted tens of thousands of active supporters and activist, like the Chicago Freedom Movement. Still other efforts had little to no popular support like the Black Liberation Armyor the Republic of New Afrika; both of which were Racial and ambitions efforts that didn’t attract as many Black people as the Integration and Reformist struggles of the CRM. It’s safe to say that the more radical the agenda or goals of a particular effort or camping, the less support or participation they got from the masses of Black people during the Civil Rights Era.
What we can’t do is reduce the Civil Rights Movement or Era down to a bunch of marches and sit-ins culminating in some political reforms and urban rights; it’s so much more than that. The CRM, for better or worse transformed the US and the world; in many positive and negative ways. It was a Reformist movement on the surface that had some Revolutionary undertones and reverberations.
Determining the exact percentage of people who made a direct positive contribution to the over all movement, that actually spans from the Reconstruction Era up to the early 1970s; or even up to now depending on how you define or measure the movement; is beyond my abilities. It’s easier to determine how many or what percentage of Black people participated or actively supported specific organizations, programs, efforts, struggles, or campaigns with in the larger movement.
If you forced me to give a solid break down anyway, I’d borrow from the Nations of Gods and Earths and lay it out like this:
5% were committed freedom fighters and organizers
85% were passive or non-committed bystanders (which by default meant the supported the oppressive status quo).
10% active Black traitors and collaborators who fought against the just aspirations of their own oppressed Race.
This is not a scientific breakdown, but it’s a pretty consistent rule of thumb, if you give or take a few percentage points; hell this breakdown down in most struggles across history and the globe. LOL. Of course I’m of the 5% in my era.
Oh, and it’s also hard to pin down a specific number because many groups had their contributions suppressed, ignored, or discounted like Black women (who represented the bulk of the unsung heroes in the struggle), Black LGBTQs (their contributions are suppressed even today, Black Integrationsist are still scared to utter even Bayard Rustin’s name), the poor illiterate Black organizers from the backwoods areas of the South (who did most of the fighting and dying), the Black urban ghetto dwellers who were often relegated to voiceless victims and pawns, and Blacks outside the US who stood in solidarity with our struggles within the Belly of the Beast.