Lupin Pharmaceuticals, an Indian transnational pharmaceutical company, develops and markets a wide portfolio of branded and generic products. The company reported the following in its 2018 annual report.

Determine the total amount that customers owe Lupin each year. (2016, 2017, and 2018)

\begin{tabular}{|l|r|r|r|} \hline \multicolumn{1}{|c}{ INR millions } & \multicolumn{1}{c|}{2018} & \multicolumn{1}{c|}{2017} & \multicolumn{1}{c|}{2016} \\ \hline Trade receivables & $44,394.7 & $36,883.0 & $39,054.4 \\ \hline Less provision for doubtful receivables & 306.9 & 318.4 & 448.2 \\ \hline Trade receivables, net & $44,087.8 & $36,564.6 & $38,606.2 \\ \hline Total assets & $140,958 & $146,544 & $127,375 \\ \hline Revenue from operations & 158,042 & 174,943 & 142,555 \\ \hline \end{tabular}