store the numbers on a system that is not connected to any other network, including other OneSpan networks, and similarly, is not connected to the Internet.
In the case of our cloud-based solutions, which involve the processing of customer information, we believe a cyber incident could have a material impact on our business. While our revenue from cloud-based solutions comprises a minority of our revenue today, we believe that these solutions will provide substantial future growth. A cyber incident involving these solutions in the future could substantially impair our ability to grow the business and we could suffer significant monetary and other losses and significant reputational harm.
To minimize the risk, we review our product security and procedures on a regular basis. Our reviews include the processes and software code we are currently using as well as the hosting platforms and procedures that we employ. We mitigate the risk of cyber incidents through a series of reviews, tests, tools and training. Certain insurance coverages may apply to certain cyber incidents. Overall, we expect the cost of securing our networks will increase in future periods, whether through increased staff, systems or insurance coverage.
While we did not experience any cyber incidents in the first six months of 2020 that had a significant impact on our business, it is possible that we could experience an incident in 2020 or future years, which could result in unanticipated costs.
Currency Fluctuation
During the three and six months ended June 30, 2020, approximately 89% and 88%, respectively, of our revenue was generated outside of the United States. While the majority of our revenues are generated outside of the United States, a significant amount of our revenue earned during the three and six months ended June 30, 2020 was denominated in U.S. Dollars. During the three and six months ended June 30, 2020, we estimate that approximately 49% and 46%, respectively, of our revenue was denominated in U.S. Dollars.
In addition, during the three and six months ended June 30, 2020, approximately 74% and 72% of our operating expenses were incurred outside of the United States. As a result, changes in currency exchange rates, especially the Euro exchange rate and the Canadian Dollar exchange rate, can have a significant impact on revenue and expenses.
In general, to minimize the net impact of currency fluctuations on operating income, we attempt to denominate an amount of billings in a currency such that it would provide a hedge against the operating expenses incurred in that currency. We expect that changes in currency rates may also impact our future results if we are unable to match amounts of revenue with our operating expenses in the same currency. If the amount of our revenue in Europe denominated in Euros continues as it is now or declines, we may not be able to balance fully the exposures of currency exchange rates on revenue and operating expenses.
The financial position and the results of operations of our foreign subsidiaries, with the exception of our subsidiaries in Switzerland, Singapore and Canada, are measured using the local currency as the functional currency. Accordingly, assets and liabilities are translated into U.S. Dollars using current exchange rates as of the balance sheet date. Revenues and expenses are translated at average exchange rates prevailing during the period. Translation adjustments arising from differences in exchange rates generated other comprehensive gain of $0.4 million for the three months ended June 30, 2020 and other comprehensive loss of $3.8 million for the six months ended June 30, 2020. For the three and six months ended June 30, 2019, translation adjustments generated other comprehensive loss of $1.3 million and $0.4 million, respectively. These amounts are included as a separate component of stockholders’ equity. The functional currency for our subsidiaries in Switzerland, Singapore and Canada is the U.S. Dollar.
Gains and losses resulting from foreign currency transactions are included in the consolidated statements of operations in other income (expense), net. Foreign exchange transaction gains aggregated less than $0.1 million for the three months ended June 30, 2020, compared to $0.2 million of gains aggregated for the three months ended June 30, 2019. During the six months ended June 30, 2020, foreign exchange transaction losses aggregated $0.5 million compared to losses aggregated of $0.7 million during the six months ended June 30, 2019.