Credibility of Rake back calculators

[Squidgy_wiji]

I have been looking at a lot of the rake back calculators online. For 50NL 6max at 40% rake back they say you should get back $3 hr 1 tabling and $13 an hour 4 tabling.

After 7983 hands at 50NL 6max, i have been raked $265.05
I have an MT ratio of 3.73 and i have played 26.13 hours according to Poker tracker.

That means i only get about $4 rake back 4 tabling as opposed to the $13 an hour all the rake back calculators say.

Are the figures computed by rake back calculators higher so more people join rakeback sites? Or are other people generating more rake than me per hour?

I have VPIP/PFR/AG =14.87/11.06/2.52