The Lean and Rind model data for 2014 has an as-yet undiagnosed flaw in the ENSO column, discovered by Jacob today.
Here's a patch to allow you to complete the assignment: Use the 2010 ENSO data in this spreadsheet here, except for the intervening years since 2010, for which use the 2014 data. be sure to add the timelags.
In the meantime, I'll try to see if I can figure out what happened with the 2014 data.
Update: Dawn found the problem. There are default-entries of "999.99"in places where the original data was missing. They're skewing the data averages. These need to be deleted and replaced with blank cells.