Classification of week of year to use as a dimension in workspace

It would be helpful if we could classify dates so that we can break metrics down by the week number in which they occur across multiple years. Currently when dropping week into workspace when using year-on-year metrics, all weeks in between the year load, making comparisons difficult. If we could use 'week of year' as a dimension we could make year-on-year comparisons in the same view much easier.