pre_text: Trade Receivables, Net The carrying amounts reported in the Consolidated Balance Sheets for Trade receivables, net approximate their fair value because of their short-term nature. A summary of Trade receivables, net of allowance for doubtful accounts is as follows (in millions): In addition to the amounts above, we have unbilled receivables that we do not expect to collect within the next year included in Other non-current assets in our Consolidated Balance Sheets. Billings for these receivables are based on contractual terms. Refer to Note 11 — Other Non-Current Assets.
table: December 31,
table: 2019 2018
table: Trade receivables — billed $136.6 $136.6
table: Trade receivables — unbilled 39.8 37.0
table: Trade receivables 176.4 173.6
table: Allowance for doubtful accounts (1.3) (1.3)
table: Trade receivables, net $175.1 $172.3
question: Analyse this data from a financial earnings document. What was the change in trade receivables between 2018 and 2019?