Vessel operations segment
(1) TCE is a non-GAAP financial measure. For a reconciliation of TCE, please see “Item 3. Key Information-A. Selected Financial Data."
Total operating revenues: Operating revenues decreased by $72.3 million to $230.7 million for the year ended December 31, 2019 compared to $303.0 million in 2018. This was principally due to a decrease of:
• $90.4 million in revenue as a result of lower utilization, higher number of drydocking days and lower charterhire rates for our fleet for the year ended December 31, 2019 compared to the same period in 2018. During the year ended December 31, 2019, the majority of our fleet was scheduled for drydocking, resulting in 278 days of off-hire in aggregate, compared to 28 days of off-hire during the same period in 2018; and
• $2.3 million decrease in vessel and other management fees revenue for the year ended December 31, 2019 compared to the same period in 2018, mainly due to the wind down of OneLNG during 2018.
This was partially offset by the:
• $20.4 million increase in revenue from the Golar Viking as she was mostly on-hire during the year ended December 31, 2019, compared to being on commercial waiting time until December 2018.
Average daily TCE: As a result of lower voyage expenses offsetting the decrease in operating revenues, the average daily TCE for the year ended December 31, 2019 increased marginally to $44,400 compared to $43,700 for the same period in 2018.
Vessel operating expenses: Vessel operating expenses decreased by $2.9 million to $67.6 million for the year ended December 31, 2019, compared to $70.5 million for the same period in 2018, primarily due to a decrease of:
• $3.1 million in reactivation and operating costs of the Golar Viking as she was taken out of lay-up in January 2018;
• $1.8 million in expenses in relation to the Gandria as a result of the generic works in anticipation of her conversion into a FLNG at the start of 2018; and
• $1.1 million in expenses in relation to the Gimi in the year ended December 31, 2019, as we commenced capitalization of costs associated with her conversion to a FLNG following receipt of the Limited Notice to Proceed in December 2018 to service the Gimi GTA Project.
This was partially offset by an increase in non-capitalizable vessel operating costs of $2.8 million net increase as a result of the scheduled drydocking in the year ended December 31, 2019.
Voyage, charterhire and commission expenses: Largely relates to charterhire expenses, fuel costs associated with commercial waiting time and vessel positioning costs. While a vessel is on-hire, fuel costs are typically paid by the charterer, whereas during periods of commercial waiting time, fuel costs are paid by us. The decrease in voyage, charterhire and commission expenses of $66.1 million to $38.4 million for the year ended December 31, 2019 compared to $104.5 million for the same period in 2018, is principally due to a decrease of:
• $56.4 million reduction in voyage expenses as a result of decreased utilization of our vessels; and
• $15.2 million reduction in bunker consumption as the majority of our fleet underwent drydocking for a total of 278 days in aggregate, compared to 28 days during the same period in 2018.
This was partially offset by the $4.6 million increase in costs in relation to the Golar Arctic, as she was mostly on commercial waiting time for the year ended December 31, 2019, compared to full utilization during the same period in 2018.
Administrative expenses: Administrative expenses decreased by $0.9 million to $50.8 million for the year ended December 31, 2019 compared to $51.7 million for the same period in 2018, principally due to a decrease in corporate expenses and share options expenses.
Project development expenses: Project development expenses decreased by $3.1 million to $2.1 million for the year ended December 31, 2019 compared to $5.2 million for the same period in 2018, principally due to a decrease in non-capitalized project-related expenses comprising of legal, professional and consultancy costs.
Depreciation and amortization: Depreciation and amortization decreased by $0.6 million to $64.9 million for the year ended December 31, 2019 compared to $65.5 million for the same period in 2018, principally due to a decrease of $0.9 million in Golar Viking depreciation for the year ended December 31, 2019, compared to the same period in 2018, as a result of a $34.3 million impairment charge on the vessel and equipment recognized in March 2019.
Impairment of long-term assets: Impairment of long-term assets increased by $42.1 million for the year ended December 31,
2019 due to a:
• $34.3 million impairment charge on vessel and equipment associated with our LNG carrier, the Golar Viking. In March 2019, we signed an agreement with LNG Hrvatska for the future sale of the Golar Viking once converted into an FSRU, following the completion of its current charter lease term. Although the sale is not expected to close until the fourth quarter of 2020, the transaction triggered an immediate impairment test. As the current carrying value of the vessel exceeds the price that a market participant would pay for the vessel at the measurement date, a non-cash impairment charge of $34.3 million was recognized. The fair value was based on average broker valuations as of the measurement date and represents the exit price in the principal LNG carrier sales market; and
• $7.3 million impairment charge associated with our investment in OLT Offshore LNG Toscana S.P.A. ("OLT-O"). In May 2019, a major shareholder in OLT-O sold its shareholding which triggered an assessment of the recoverability of the carrying value of our 2.6% investment in OLT-O. As the carrying value of our investment exceeded the representative fair value, we wrote off our investment.
Other operating gains: Other operating gains comprised of:
• $9.3 million and $50.7 million recovered in connection with the ongoing arbitration proceedings arising from the delays and the termination of the Golar Tundra time charter with a former charterer, for the year ended December 31, 2019 and 2018, respectively. The amount for the year ended December 31, 2019 represents the final payment to settle these proceedings; and
• $4.0 million loss of hire insurance proceeds on the Golar Viking for the year ended December 31, 2019.
Table:
 |  | December 31, |  | 
(in thousands of $, except average daily TCE) | 2019 | 2018 | Change | % Change
Total operating revenues | 230,654 | 302,979 | (72,325) | (24)%
Vessel operating expenses | (67,601) | (70,543) | 2,942 | (4)%
Voyage, charterhire and commission expenses (including expenses from collaborative arrangement) | (38,381) | (104,463) | 66,082 | (63)%
Administrative expenses | (50,801) | (51,716) | 915 | (2)%
Project development expenses | (2,050) | (5,165) | 3,115 | (60)%
Depreciation and amortization | (64,945) | (65,496) | 551 | (1)%
Impairment of long-term assets | (42,098) | — | (42,098) | 100%
Other operating gains | 13,295 | 50,740 | (37,445) | (74)%
Operating (loss)/income | (21,927) | 56,336 | (78,263) | (139)%
Equity in net losses of affiliates | (22,565) | (138,677) | 116,112 | (84)%
Other Financial Data: |  |  |  | 
Average Daily TCE (1) (to the closest $100) | 44,400 | 43,700 | 700 | 2%
Calendar days less scheduled off-hire days | 3,840 | 3,987 | (147) | (4)%


Question: What accounted for the change in administrative expenses?
Answer: Due to a decrease in corporate expenses and share options expenses.