"There's lies, damned lies, and statistics."
You're looking at these numbers and just start screaming at a bunch of liberal white people that they're "racist as fuck." Well, what did you EXPECT the numbers to be? I'm not surprised at all that they're what you posted. It's exactly what I'd expect given the state of the education system.
Blacks are 13% of the population. But they're not going to be 13% of the screenwriters or any other complicated profession unless those populations are equally educated. They're not. There's a HUGE difference in the quality of the elementary schools, middle schools, and high schools blacks attend. Take a look at this:
These are numbers, too. 85% of whites going to a top performing school, 6 percent of blacks. So did you really expect blacks to show up as professional writers if they go to a failing school that doesn't teach them to write in the first place?
If 3/4 of blacks go to terrible schools until they're 18, that 3/4 is never going to be competitive as writers. They're probably not even going to try. And you're not going to see 13% of screenwriters be black even if people are trying their best NOT to discriminate.
Is that racism? Partly. Partly it's shitty parenting caused by the breakdown in the black family in the 70's. Partly it's a bunch of other shit too including just the rich getting richer and spending more on their kids. So maybe you should focus on fixing the education system instead of hurling insults at people based on their skin color. Frankly, you're being "racist as fuck" in the assumptions you're making. You can't fix this shit by waiting until somebody's 25 and then saying "yeah let's make you a writer." You have to fix it when they're learning to read at age 4 or 5 or 6. And you're not going to get any allies in doing that by acting like a racist asshole.