We are able to mix this amount based on what we and our partners hold
Who exactly are your partners (just don't tell me it's chinese and russian miners) and how do you know how much of their coins is available?...
We have a partnership with them as exclusive , this balance are in an address that is connected to our API in the system. We are able to see the available balance in realtime so we know how much coins are able to dispense. We are not a mixing service that can handle any amount. We have a limit for our fresh coins therefore we have to implement this mechanism. As now we have no Litecoin so we dont mix that until we get litecoin. If tomorrow we run out of Monero, we cant mix Monero. Thats why we have to display the coins available as this may change daily. There is only x number of fresh coins compared to mixing where its unlimited .
Thats why our website has the amount that can be mixed. Hope this clears why we have the statistics displayed