help with formula (multi-year week number and fillblock)

[mrfuzzylogic]

Hello all,

I have a spreadsheet that creates a Gant chart and fills in the cells to the right to graphically show the duration and percentage completed. Works fine as long as it's in the same year and/or less than 52 weeks. My question is this, how would I change the formula to calc and fill in if the project runs over 52 weeks and/or runs across two or more years?
=IF(AND(COLUMNS($G$5:G5)>=$C5,COLUMNS($G$5:G5)<=$D5),IF(COLUMNS($G$5:G5)-$C5<ROUND(($D5-$C5+1)*$F5,0),fillblock,""),"")

I added the number of weeks column too. I was thinking I would add that in manually.