$($Related to Checkpoint $18\mathrm{.}1)($Measuring firm liquidity$)$ The following table contains current asset and current liability balances for Deere and Company $($DE$)$:

a$.$ Measure the liquidity of Deere & Co$.$ for each year using the company's net working capital and current ratio.

b$.$ Is the trend in Deere's liquidity improving over this period?