Try the following array formulas that need to be confirmed with CONTROL+SHIFT+ENTER, not just ENTER...
=MAX(SUBTOTAL(1,OFFSET(B1:B20,ROWS(B1:B20)-ROW(INDIRECT("1:"&13-2)),0,-3)))
or
=MAX(SUBTOTAL(1,OFFSET(B1:B20,ROWS(B1:B20)-ROW(INDIRECT("1:"&D1-2)),0,-3)))
...where D1 contains the number of years of interest, such as 13. Adjust the range accordingly.
Hope this helps!