Add 60 columns to the right titled 1 ... 60 and have a formula in the rows below them (columes E and further) of the sort:
=IF(AND($B2<=E$1;$C2>=E$1);1;0)
Then sum up for each minute column and you have your count. I have to say CAPSLOCKs answer works in the newer Excel versions. I recommend using his approach for the neater way you are looking for!