You could edit the x-axis (right click on axis -> Edit Axis) and set a Fixed range for the month of July. This means that you are not filtering out the previous data but just selecting what to view.
So the answer by Emiliano is correct as far as it goes, but I've just had the question thrown back at me by one of our users. He is using the Reader, and wants to zoom in on the data using the Quick Filter options. Set to 'This Year', we see all the data. Set it to this week, and it shows me only the counts for this week - starting from zero. This is of no use to him (or me, or anyone). It would be fine to have that as an option, but we're often wanting to see very specific details about the last week - including a running total, starting at the start of that time period at the correct figure - so showing me 100 - 150, for example, instead of 0 to 50.