Activity Monitor suddenly showing all cores in Dock icon After upgrading my MBP from Mavericks to Yosemite, the "CPU History" option of the Activity Monitor only showed one aggregate graph.

After reinstalling Yosemite from scratch, I suddenly have 8 tiny graphs, one for each core, which I find too tiny to be useful. Is there any way to switch the Dock icon of Activity Monitor back to the single graph?
I saw this on a fresh install on 10.10.4. To fix it, close Activity Monitor and then:

defaults write com.apple.activitymonitor IconType -int 4