At a glance at the linked source data, it looks like Seattle came in with the lowest values on this list, at 47 murders for 2020 vs 27 in 2019.
One thing of note is that some of the values appear to be for not quite the entirety of 2020.
The first sentence of the story's second paragraph includes a link to a Twitter post [1] from the person who compiled the data, which contains a second link [2] to the Google Doc that he created.
1 - https://twitter.com/Crimealytics/status/1343950694672379905
2 - https://docs.google.com/spreadsheets/d/1Z9b5mIwztAwmEHJW7Q5D...