If you have access to logs you could just check the number of request happening each minute.
For example:
cat app-access*.log | cut -f 1 -d " " | rev | cut -c 4- | rev | lxsort -u | uniq -c | sed "s/ */ /g" | sed "s/|\[/ /" | sed "s/ /\t/g" >goo.txt
cat all the access logs into cut to pull off just the ip and date time.
Flip the line to remove the seconds and push into a unique sort (sort on linux on my windows box I renamed linux sort to lxsort so I didn't use the window sort command).
Then get a count of the number of unique accesses for a given minute by IP address
Do some text cleanup with sed.
Drop this file into Excel and pivot on the datetime field.
V/r,
Gene