December 31, 2020. These expenses increased at a higher rate than our revenues, primarily as a result of expenses associated with the accelerated launch of new products and changes in product mix. We also experienced increased expenses related to costs of outsourcing production to third parties as a result of the growth in sales.
Employee benefits expense increased by €19,861 thousand, or 202.6%, for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to an increase in personnel expenses stemming from hiring of employees to support the growth of Wallbox.
Other operating expenses increased by €35,213 thousand, or 429.8%, for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to increases of (i) €15,224 thousand of professional services and fees which includes €8,046 thousands corresponding to the non-incremental or directly attributable costs to the issuance of shares per the Business Combination, (ii) marketing of €5,977 thousand related to the high investment and publication of the Business Combination, and (iii) €2,702 thousand related to increased delivery costs in connection with increases in sales and production.
Amortization and depreciation increased by €6,104 thousand, or 256.6%, for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to investments in leasehold improvements to the leased headquarters in Barcelona and capitalization of internally developed intangibles with respect to EV chargers.
Net other income increased by €367 thousand, or 127.0%, for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to government subsidies recognized.
Net Financial Loss
Financial income increased by €149 thousand for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to additional interest over loans to the Joint Venture (€55 thousand) and €83 thousand of investments fair valuation at year end.
Financial expenses increased by €31,056 thousand for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to a fair value loss incurred on a newly issued convertible loan during the year and the incurrence of new bank loans and working capital credit lines.
Change in fair value of derivative warrant liabilities increased by €68,953 thousand for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to the increase in price per warrant from the amounts as of the Business Combination date.
A one-time, non-cash listing expense of €72,172 thousand was recognized in accordance with IFRS2 as part of the Business Combination for the year ended December 31, 2021.
Foreign exchange gains increased by €1,096 thousand for the year ended December 31, 2021 as compared to the year ended December 31, 2020, primarily due to fluctuations in GBP, USD and the Norwegian Krone against the Euro.
Share of Loss of Equity-Accounted Investees
Share of loss of equity-accounted investees decreased by €253 thousand, or 100%, for the year ended December 31, 2021 as compared to the year ended December 31, 2020, as a result of a net book value of the Joint Venture at zero as of December 31, 2021. For the year ended December 31, 2020, the Joint Venture losses were limited to the amount of the net book value (€253 thousand) of such Joint Venture.
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