Calculating Year to Date returns

Hi guys,

I'm just trying to calculate YTD (year-to-date) returns on a timeseries. Please see the excel file - Column A has the dates, Column B -the values.
I've manually calculated the returns for 2009 and 2010, but I need to get a formula or vba code that will do this.
A code that can detect the MOst RECENT date and divide the corresponding Column B value by the previous year end value (ie 31 Dec) to compute the return.

Any suggestions?


thanks