Everyday a new line of data is added to the bottom of a report. What has to
be done, in a summary report (found on a different tab) is to subtract
yesterday's value from today's value.

The equation below works - however I would like to know if there is a better
one.

=INDEX('Running total'!G21:G1040,COUNT('Running
total'!G21:G1040))-INDEX('Running total'!G21:G1040,COUNT('Running
total'!G21:G1040)-1)

Right now the data goes to about row 200.

Thanks in advance.