Cullumber Bancorp has made an investment in banking software at a cost of $$1,816,200.$ If management expects productivity gains and cost savings to generate additional cash flows of $$476,900,$ $$727,600,$ $$867,600,$ and $$439,600$ over the next four years, what is the investment's payback period? $($Round answer to $2$ decimal places, e$.$g$.15\mathrm{.}25.)$ Payback period is years