Count the Time in excel columns

Hello,

I have a requirement, in a column the time is displayed as below, now i need for the date 10/9/2010 i need the count of B2 for every one hour eg: 4 records during time interval 10:00:00 to 10:59:59
A2 B2
10/9/2010 12:00:00 AM
10/9/2010 10:00:22 PM
10/9/2010 10:02:28 PM
10/9/2010 10:26:32 PM
10/9/2010 10:32:28 PM
10/9/2010 11:22:28 PM
10/9/2010 11:32:28 PM
10/9/2010 11:42:28 PM
10/9/2010 11:52:28 PM
10/10/2010 12:00:23 AM
10/10/2010 12:01:10 AM
10/10/2010 12:01:24 AM
10/10/2010 12:01:25 AM
10/10/2010 12:01:35 AM
10/10/2010 12:42:28 AM
10/10/2010 12:52:28 AM

please help me.

Regards,
sindhuG.