Bubble chart / scatter plot problem

I have a matrix of data showing the number of vehicles that entered a car park at a certain time and left at a certain time. I'd like to show the data on a bubble chart, with the arrival time on the x-axis, the departure time on the y-axis and the size of the bubble corresponding to the number of vehicles that arrived and departed at the intersection of the arrival and departure time.

The data is attached. For example, I'd like a bubble of relative size 9 plotted at the intersection of arrival time 0830 and departure time 0900 and one of relative size 1 plotted at the intersection of arrival time 0700 and departure time 0830.

I'm having difficulty getting Excel to a) display the times correctly, b) ignore the zeroes and c) show the bubble size in relation to the number of vehicles. Any suggestions?

Thanks, will give that a try.