pre_text: a. For the years ended December 31, 2017, 2018 and 2019, the Company recognized NT$118,252 million, NT$123,795 million and NT$122,999 million, respectively, in operating costs, of which NT$2,256 million, NT$1,698 million and NT$820 million in 2017, 2018 and 2019, respectively, were related to write-down of inventories. b. None of the aforementioned inventories were pledged.
table: As of December 31,
table: 2018 2019
table: NT$ NT$
table: (In Thousands) (In Thousands)
table: Raw materials $3,766,056 $5,102,571
table: Supplies and spare parts 3,133,737 3,548,376
table: Work in process 10,034,488 11,309,718
table: Finished goods 1,268,838 1,754,137
table: Total $18,203,119 $21,714,802
question: Analyse this data from a financial earnings document. What was the average Supplies and spare parts?