Yeah I'm in the same boat. I use google for almost everything, so I know I have a + account, but this chart says these sites were "used or contributed to". Which again, might make it a b.s. stat since now all Youtube comments are posted to the + account automatically.I guess technically I'm always logged into Google+ because I'm always using Chrome/Gmail/Google Music/Google Drive every single day, but I haven't legitimately looked at Google+ itself in over a year.