Nano Specialist is considering an upgrade project. The estimated cash flows from the upgrade project appear below. What is the project's payback period? Note that year $0$ and year $1$ cash flows are negative. $($Answer in years, round to $2$ places$)$

Year $0$ cash flow $=-87,000$

Year $1$ cash flow $=-54,000$

Year $2$ cash flow $=16,000$

Year $3$ cash flow $=43,000$

Year $4$ cash flow $=23,000$

Year $5$ cash flow $=43,000$

Year $6$ cash flow $=39,000$

Year $7$ cash flow $=25,000$

Answer: