THIS WAS A CLOSE REPLY

Maybe something like this

Assuming K4 = 2007; L4=2008; M4=2009; N4=2010; O4=2011;P4=2012

Array-formula in K5
=SUM(IF(YEAR($B$5:$B$200)=K$4,IF($C$5:$C$200="",TO DAY(),IF(YEAR($C$5:$C$200)K$4,DATE(K$4,12,31),$C$ 5:$C$200))-$B$5:$B$200))

confirmed with Ctrl+Shift+Enter
(hold down both Ctrl and Shift keys and hit Enter)

copy across till P5

M.