The "bottom line" question for Java garbage collection is: what's the proportion of time spent in garbage collection? When garbage collection is running, either the application is not running (e.g. full GC), or application throughput is affected (e.g. concurrent collection). Less than 10% is good. Less than 1% is ideal.
The IBM Garbage Collection and Memory Visualizer Tool is an awesome, free, supported tool for analyzing verbosegc and reports this statistic in its "Report" tab; however, by default, it reports the percentage for the entire file. Zooming in on the line plot doesn't change this, but instructions have been added to the cookbook on how to change this by updating the X-axis minimum and maximum: https://publib.boulder.ibm.com/httpserv/cookbook/Major_Tools-Garbage_Collection_and_Memory_Visualizer_GCMV.html#Major_Tools-Garbage_Collection_and_Memory_Visualizer_GCMV-Cropping_Data_Analysis