Crossyear week

[Astolfo]

Hi all,

i have a problem, i divide the commercial calendar in 52 weeks, it starts the first monday of january and ends the sunday before the monday of the next year, considering almost every year week 52 won't start on monday 25 days of week 52 will be splittered between 2 years, how can i show this considering i have to calculate also the YTD ?

Thanks