Generate a list number of visits at different times in a day

I want to graph the number of visits we receive at different times throughout the day in half hour increments. The times are recorded in hours and minutes for each individual visit. How can I generate a list that counts the number of visits for example between say from 10:00AM to 10:29AM, 10:30AM to 10:59AM, 11:00AM to 11:29AM and so on for the whole day? My apologies if this is the wrong place to post this question.

One idea ..
Assume your source time data is in A2:A10

Input
in C2: 10:00 AM
in C3: 10:30 AM
Select C2:C3, copy down

Then place
in D3: =TEXT(C2,"h:mm AM/PM")&"-"&TEXT(C3,"h:mm AM/PM")
in E3: =SUMPRODUCT(($A$2:$A$10>=C2)*($A$2:$A$10<C3))
Copy D3:E3 down. Now you can graph it based on col D (time bucket labels) and col E (counts)
---------------------------------
Any good? Wave it, hit the little star at the bottom left of my responses