Line spacing in tick labels

I have a chart that plots a series of values over time. The x-axis number format is mm/dd/yyyy hh:mm:ss and I have a line break to place the date and time on two separate lines. However the line spacing seems to be wasting a lot of spacing (it looks like double spaced font to me). Is there any way to change this? It might not seem like a big deal but I have a specific use for these charts that would really benefit from being able to use that extra space for a larger plot area.

I've attached a sample file.

Thanks in advance.

Perfect.

I had seen a few references to the ASCII line break command before but I forgot about it and didn't know how to use it here. Thanks.