Probably referring to this Washington Post data set:

https://www.washingtonpost.com/graphics/investigations/polic...

If you query the data set it looks like 38 unarmed black men were shot by police in 2015.

To determine likelihood of a random “black porch pirate” being shot by police, we should look at the % of police encounters that end in unarmed shoots.

I found a random quota post [1] that says the number of police encounters in 2015 was around 53,469,300.

Back of a cocktail napkin numbers show that we’re talking about something in the neighborhood of .00006% of encounters end in an unarmed black person being shot by the police.

[1] https://www.quora.com/What-is-the-estimated-number-of-police...