Averaging Values In Column B For Recurring Dates In Column A

I have a set of data with daily total returns (TR) for 218 companies on the FTSE350 between 2007-2013. The Data looks as follows:

Company ..............Date(daymonthyear)..... TR
1........................... 112007 ..........................10.4
1 .......................... 212007 ..........................10.2
1 .
1 . .
1 .......................... 30102013 .........................12.3
. . . .
. . .
. . .
2............................112007 .......................... 4.5
2 ............................212007 ..........................4.6
2 .
. .
. .
Etc.
. .
. .
218.......................30102013 .....................13.2

I want to perform a dickey fuller test to see if there is a unit root, but for this I can’t have repeated time values, thus I need to create a daily average TR for each day (Thus summing up all TR values for all companies that have data on TR available on that day and averaging them).

How in excel can create an average value for TR every time a series of numbers in the “date” column take the same value? The best thing possible would then be if this could appear so that I have a data set that looks like

Date (daymonthyear)........ TR
112007 ..............................13.2
.
.
.
.
30102013............................ 9.4