Results of Operations
Year Ended December 31, 2018 Compared to Year Ended December 31, 2019
During the year ended December 31, 2019, we had an average of 27.2 ships operating in our owned and bareboat fleet (including ships owned by the Partnership), having 9,518 revenue operating days and an average of 27.2 ships operating under our technical management (including 27.0 of our owned and bareboat ships). During the year ended December 31, 2018, we had an average of 26.0 ships operating in our owned and bareboat fleet (including ships owned by the Partnership), having 9,030 revenue operating days and an average of 25.5 ships operating under our technical management (including 25.0 of our owned and bareboat ships).
Revenues: Revenues increased by 8.1%, or $50.3 million, from $618.3 million during the year ended December 31, 2018 to $668.6 million during the year ended December 31, 2019. The increase in revenues is mainly attributable to an increase of $63.4 million deriving from the full operation of the GasLog Houston, the GasLog Hong Kong and the GasLog Gladstone which were delivered on January 8, 2018, March 20, 2018 and March 29, 2018, respectively and the deliveries of the GasLog Gladstone on March 15, 2019 and the GasLog Warsaw on July 31, 2019. These deliveries resulted in an increase in revenue operating days. In addition, there was an increase of $11.0 million from our vessels trading in the spot and short-term market including the impact of the unscheduled dry-dockings of the GasLog Savannah, the GasLog Singapore and the GasLog Chelsea and an increase of $2.7 million from the remaining fleet. The above increases were partially offset by a decrease of $26.1 million from the expiration of the initial time charters of the GasLog Shanghai, the GasLog Santiago, the GasLog Sydney, the GasLog Skagen, the GasLog Saratoga and the Methane Jane Elizabeth and a decrease of $0.7 million due to increased off-hire days from the remaining vessels. The average daily hire rate increased from $68,392 for the year ended December 31, 2018 to $70,167 for the year ended December 31, 2019.
Table:
 |  | Year ended December 31, | 
 | 2018 | 2019 | Change
Amounts are in thousands of U.S. Dollars |  |  | 
Revenues | $618,344 | $668,637 | $50,293
Net pool allocation | 17,818 | (4,264) | (22,082)
Voyage expenses and commissions | (20,374) | (23,772) | (3,398)
Vessel operating and supervision costs | (128,084) | (139,662) | (11,578)
Depreciation | (153,193) | (168,041) | (14,848)
General and administrative expenses | (41,993) | (47,385) | (5,392)
Impairment loss on vessels | — | (162,149) | (162,149)
Profit from operations | 292,518 | 123,364 | (169,154)
Financial costs | (166,627) | (190,481) | (23,854)
Financial income | 4,784 | 5,318 | 534
Loss on derivatives | (6,077) | (55,441) | (49,364)
Share of profit of associates | 1,800 | 1,627 | (173)
Total other expenses, net | (166,120) | (238,977) | (72,857)
Profit/(loss) for the year | 126,398 | (115,613) | (242,011)
Non-controlling interests | 78,715 | (14,952) | (93,667)
Profit/(loss) attributable to owners of the Group | $47,683 | $(100,661) | $(148,344)


Question: What was the change in revenue from 2018 to 2019?
Answer: $50.3 million