Table:
|  | Year Ended December 31, |  |
| --- | --- | --- |
| (in thousands of U.S. dollars, except calendar-ship-days) | 2019 | 2018 |
| Revenues | 943,917 | 776,493 |
| Voyage expenses | (402,294) | (381,306) |
| Vessel operating expenses | (208,601) | (209,131) |
| Time-charter hire expense | (43,189) | (19,538) |
| Depreciation and amortization | (124,002) | (118,514) |
| General and administrative expenses | (36,404) | (39,775) |
| Write-down and loss on sale of vessels | (5,544) | 170 |
| Restructuring charges | — | (1,195) |
| Income from vessel operations | 123,883 | 7,204 |
| Equity income | 2,345 | 1,220 |
| Calendar-Ship-Days (1) |  |  |
| Conventional Tankers | 22,350 | 21,226 |
Paragraphs:
Operating Results – Teekay Tankers
The following table compares Teekay Tankers’ operating results, equity income and number of calendar-ship-days for its vessels for 2019 and 2018.
(1) Calendar-ship-days presented relate to owned and in-chartered consolidated vessels.
Teekay Tankers' income from vessel operations increased to $123.9 million in 2019 compared to $7.2 million in 2018, primarily as a result of: • an increase of $129.3 million due to higher overall average realized spot tanker rates earned by Teekay Tankers' Suezmax, Aframax and LR2 product tankers; • an increase of $3.5 million due to improved net results from Teekay Tankers' full service lightering (or FSL) activities from more voyage days and higher realized spot rates earned;
• an increase of $3.4 million resulting from lower general and administrative expenses primarily due to non-recurring project expenses incurred in 2018; • a net increase of $2.3 million primarily due to the delivery of three Aframax and two LR2 chartered-in tankers in late 2018 and throughout 2019, partially offset by the redeliveries of various in-chartered tankers to their owners in the second and third quarters of 2018; and • an increase of $1.2 million as a result of restructuring charge incurred in the prior year;
partially offset by
• a decrease of $10.2 million due to a higher number of off-hire days in 2019 resulting from dry dockings and higher off-hire bunker expenses compared to the prior year; • a decrease of $6.9 million due to lower revenues and loss on the sale of one Suezmax tanker in 2019 and the write-down of two Suezmax tankers that were classified as held for sale at December 31, 2019; and • a decrease of $6.4 million due to the amortization of first dry dockings for various former Tanker Investments Ltd. (or TIL) vessels subsequent to Teekay Tankers' acquisition of TIL in late 2017.
Equity income increased to $2.3 million in 2019 from $1.2 million in 2018 primarily due to higher earnings recognized in 2019 from the High-Q Investment Ltd. joint venture as a result of higher spot rates earned in 2019.
Question:
What was the increase in Teekay Tankers' income from vessel operations in 2019?
Answer: $123.9 million