Is the data already compiled? Then set it up as in the table under the
"Dynamic Do-It-Yourself Histograms" heading in the page I cited:
http://peltiertech.com/Excel/Charts/Histograms.html
(about halfway down), but instead of the formulas, just enter your counts.
To make it easier, just enter the time ranges in column A (e.g., enter
13:00 - 13:30 in A2, 13:30 - 14:00 in A3, etc.). Then enter the first set of
counts in column B, the next in C, etc. Make a histogram (column chart) with
the data in A2 to Bwhatever. Copy the chart, go to Chart menu > Source Data
Series tab, and change the range in the Values box from column B to column
C. Repeat for the rest of your columns.
- Jon