Other non-operating results
The following details our other consolidated results for the years ended December 31, 2018 and 2017:
Interest income: Interest income increased by $4.2 million to $10.1 million for the year ended December 31, 2018, compared to $5.9 million for the same period in 2017 due to returns on our fixed deposits that had been made in 2018, and income derived from the lending capital of our lessor VIEs, that we are required to consolidate under U.S. GAAP.
Interest expense: Interest expense increased by $42.6 million to $101.9 million for the year ended December 31, 2018 compared to $59.3 million for the same period in 2017. In addition to higher LIBOR rates, this was primarily due to:
• $22.7 million increase in interest expense arising on the loan facilities of our consolidated lessor VIEs (refer to note 5 "Variable Interest Entities ("VIE")" of our consolidated financial statements included herein), in particular on the Hilli post-delivery sale and leaseback arrangement entered into during June 2018;
• $21.7 million lower capitalized interest on borrowing costs in relation to our investment in the Hilli FLNG conversion prior to acceptance of the vessel;
• $7.0 million increase in amortization of deferred financing costs in relation to the Hilli facility; and
• $1.4 million increase in interest expense in relation to the $402.5 million convertible bond issued in February 2017, resulting in a full year of interest incurred in 2018.
This was partially offset by a decrease of:
• $5.9 million in interest expense relating to the Hilli disposal; and
• $5.0 million higher capitalized interest on borrowing costs in relation to our investment in Golar Power.
(Losses)/gains on derivative instruments: Losses on derivative instruments increased by $51.2 million to a loss of $30.5 million for the year ended December 31, 2018 compared to a gain of $20.7 million for the same period in 2017. The movement was primarily due to:
Net unrealized and realized gains on interest rate swap agreements: As of December 31, 2018, we have an interest rate swap portfolio with a notional amount of $950 million, none of which are designated as hedges for accounting purposes. Net unrealized gains on the interest rate swaps decreased to a gain of $0.6 million for the year ended December 31, 2018 compared to a gain of $6.6 million for the same period in 2017, due to an improvement in the long-term swap rates, offset by the decreased notional value of the swap portfolio over the period. Realized gains on our interest rate swaps increased to a gain of $8.1 million for the year ended December 31, 2018, compared to a loss of $3.8 million for the same period in 2017. The increase was primarily due to higher LIBOR rates for the year ended December 31, 2018.
Unrealized (losses) gains on Total Return Swap (or equity swap): In December 2014, we established a three month facility for a Stock Indexed Total Return Swap Programme or Equity Swap Line with DNB Bank ASA in connection with a share buyback scheme. The facility has been extended to June 2019. The equity swap derivatives mark-to-market adjustment resulted in a net loss of $30.7 million recognized in the year ended December 31, 2018 compared to a gain of $16.6 million for the same period in 2017. The loss in 2018 is due to the fall in our share price during 2018.
Unrealized mark-to-market losses on Earn-Out Units: This relates to the mark-to-market movement on the Earn-Out Units issuable in connection with the IDR reset transaction in October 2016, which we recognize as a derivative asset in our consolidated financial statements. The decrease in Golar Partners' quarterly distribution to $0.4042 per common unit on October 24, 2018 resulted in the contingent Earn-Out Units arising out of the IDR reset transaction in October 2016 not crystallizing and, accordingly, we recognized a mark-to-market loss of $7.4 million for the year ended December 31, 2018, effectively reducing the derivative asset to $nil at December 31, 2018, compared to a gain of $0.4 million for the same period in 2017.
Net income attributable to non-controlling interests: The net income attributable to non-controlling interests comprises of (i) $19.7 million and $1.5 million in relation to the non-controlling shareholders who hold interests in Hilli LLC and Hilli Corp (prior to the incorporation of Hilli LLC) for the year ended December 31, 2018 and 2017, respectively, and (ii) $43.5 million and $32.9 million in relation to the equity interests in our lessor VIEs for the year ended December 31, 2018 and 2017, respectively.
Table:
 |  | December 31, |  | 
(in thousands of $) | 2018 | 2017 | Change | % Change
Total other non-operating expense | — | (81) | 81 | (100)%
Interest income | 10,133 | 5,890 | 4,243 | 72%
Interest expense | (101,908) | (59,305) | (42,603) | 72%
(Losses)/gains on derivative instruments | (30,541) | 20,696 | (51,237) | (248)%
Other financial items, net | (1,481) | (69) | (1,412) | 2,046%
Income taxes | (1,267) | (1,505) | 238 | (16)%
Net income attributable to non-controlling interests | (63,214) | (34,424) | (28,790) | 84%


Question: What accounted for the increase in interest income?
Answer: Due to returns on our fixed deposits that had been made in 2018, and income derived from the lending capital of our lessor VIEs, that we are required to consolidate under U.S. GAAP