As of last summer, a streamlined way for calculating annual glare within the grasshopper interface was not available. No update since.
You may want to consider running the glare assessment for a smaller time period and extrapolate those findings to give you you a better sense of glare persistence. For example, I may run simulations between 8-11am for every other day between June 1 and July 30 to get a sense of glare potential on the east facade around the summer solstice. Be careful to consider if your climate and sky condition is equal throughout the time frame and understand that this will take a long time given simulation parameter settings. Running on "lowest" will give initial results and lead you in the right direction for your design but be sure to up the Radiance parameters and retest when you hone in on your design. Lastly, given your scoped assessment period, be sure to understand potential for glare at other hours so you can speak confidently about how your design measures will respond to times outside your simulation.
I hope this helps and perhaps one of the developers will chime in with an update to the annual glare assessment within GH.
Please refer to this post for how to create a time series for simulation: