Rather than setting a card to show Year to Date, or Last 12 Months, etc. - I would like to have the option to set the number of time periods that I want a card to display.  For example, if I set a card to display 6 time periods and then choose to graph the data by month, I would see the last 6 months.  If I then choose to display the data by year, I would see the last 6 years.