I'l have a crack Arnold, and I don't even know where you work, I assume yr an engineer. I'l preface it by saying that your employer needs to train you to a minimum standard and provide conditions that enable you to meet all regulatory obligations without undue fatigue or difficulty.
I think you should be paid $1 more than the amount at which you will leave in search of work elsewhere. (ie what the market thinks you're worth)
So by my book the salary should change depending on the demand for your skills, if the outfit down the road is willing to pay more, then you should be paid $1 more than it takes to keep you in your current job. (that doesn't mean $1 more than they are offering).
So what is Arnold worth? That depends on the labour pool he is part of. If the companies that need his skils can only draw from an Australian labour pool he'd be worth quite a lot. If they could access a global pool then he'd be worth significantly less.
What is happening to the labour market this decade?