Its not always the case that every piece of data that you have in a visualization will be relevant. you may wish to think about how you can direct the viewers attention to the part you want to talk about, there are 2 main ways to do this.
Filtering
Filtering is a way to remove any information that isn't relevant to what you want to direct the user to. This has its pros and Cons,
Pro - it makes sure the user is only interested in the information you are presenting and cant get distracted by other information.
Con - it removes context from the visualization, you cant necessarily tell the scale of the data in comparison to the rest of the data set
Highlight
Highlight is showing all of the data grayed out with the section of the data you want the user to focus on in a different colour
Pro - it keeps the context of the data you're looking at, and allows the user to see that comparison
Con - if you're looking at a lot of data this can become quite messy
So which should you use? Its up to your discretion, I would personally more often than not choose the Highlighting function, however if the data is too large I would choose to keep a few top and bottom values and filter out the rest in order to keep context for the user