Gantt chart - how to set matrix visual always be expanded - toggle button (2 bookmarks)

Hi, 
I am using Gantt chart to show the data for previous year and current year . I did it and using toggle button(2 bookmarks) to show previous year and the current year data.

Question:
By default the matrix shows current year data, once the toggle button moved, the previous year data shows previous year data , but here the matrix got collpased , so manually i am drill down and expanding the rows each and every time when i use toggle button. 
Is there any way to restrict to display the matrix data always expand by default ???

Your inputs please?