OK. My desire to see the total amount of time I have spent reviewing Anki cards finally surpassed my laziness and I spent several hours hacking Anki plugins to concoct one myself. I remember Nuke Marine wanted it and there has been a request for it sitting on the Anki site for a whole so I thought there may be people out there who wants it too. I shared it by the name of Total Review Time. It basically just displays the sum of the review time of all cards under the Review Time graph. I'm a total noob to the programing language used by Anki but I'm not updating any record so it shouldn't do anything bad to your decks. Still, it's probably a good idea, it's always a good idea, to take a backup before using it.

Now I can say I memorized 3672 words in exactly 106.3 hours, and I'm a happy OCD free person again.

I'm not sure if its what you wanted but there is info about your total review time for a deck when you hover over those two bars in status bar (just next to your time left estimation).

Just check your plugin and there is some disparity between both counts:
Plugin = 299.96 hours
Status bar = 17.6 days = 422.4 hours

Thanks for trying out, I didn't know you can see it there, haha. I might as well add a bit more function I guess then. Mine comes out spot on though. Do you have any suspended cards?

Yes, I have around 1k suspended cards but they are all "new" and I've never seen any of them. It might be caused by other cards I had in this deck (sentences) which I deleted at some point, this way it would make sense. Your plugin counts time spent on current cards and status bar counts every card you've ever worked on.

You are right, it was deleted cards that messed it up. The plugin now reads the record from another place, so it should be consistent. I also added a function so it now shows the total of the given period, i.e. if the graph is showing 7 days, it gives you the total for that 7 days.

edit:
I found a bug. I was showing total for 6 says in the 7 day graph. If you downloaded it before 8:00PM US mountain time, and your 7 days' total seems a bit short, Please re-download. I fixed it right away but there may be one person who got the one with the bug.

Now it works great and its more accurate than what status bar says:
Plugin = 425.24 hours
Status bar = 17.71 days = 425.04 hours

Great, thanks for the update. At least my several hours were not totally in vain. I made a minor correction to the calculation logic, and changed the displaying format to 'x hours, x minutes' and also added average per day. Wait, is my OCD getting worse? I totally wasn't planning for this, just wanted a hack, but oh well.