| ● | Periodic restoration of previously reduced compensation programs |
| ● | Substantial legal, banking and advisory professional service fees incurred in connection with the proxy solicitation contest initiated by New Mountain Vantage Advisers LLC as well as the Baring Transaction |
| ● | Increase in interest expense related to an increase in our outstanding debt under our credit facility |
High repeat business and client concentration are common in our industry. During the three months ended December 31, 2020 and 2019, 97% and 96%, respectively, of our revenue was derived from clients who had been using our services for more than one year. During the nine months ended December 31, 2020 and 2019, 96% and 97%, respectively, of our revenue was derived from clients who had been using our services for more than one year. Accordingly, our global account management and service delivery teams focus on expanding client relationships and converting new engagements to long-term relationships to generate repeat revenue and expand revenue streams from existing clients. We also have a dedicated business development team focused on generating engagements with new clients to continue to expand our client base and, over time, reduce client concentration.
We derive our revenue from two types of service offerings: application outsourcing, which is recurring in nature; and consulting, including technology implementation, which is non-recurring in nature. For the three months ended December 31, 2020, our application outsourcing and consulting revenue represented 57% and 43%, respectively, of our total revenue as compared to 55% and 45%, respectively, for the three months ended December 31, 2019. For the nine months ended December 31, 2020, our application outsourcing and consulting revenue represented 56% and 44%, respectively, of our total revenue as compared to 56% and 44%, respectively, for the nine months ended December 31, 2019.
In the three months ended December 31, 2020, our North America revenue increased by 2.1%, or $5.3 million, to $256.5 million, or 74.1% of total revenue, from $251.2 million, or 75.0% of total revenue, in the three months ended
December 31, 2019. In the nine months ended December 31, 2020, our North America revenue decreased by 1.4%, or $10.1 million, to $713.9 million, or 74.0% of total revenue, from $724.0 million, or 73.7% of total revenue in the nine months ended December 31, 2019. The increase in North America revenue for the three months ended December 31, 2020 was primarily due to revenue from several tuck-in asset and business acquisitions closed in the fiscal year ended March 31, 2020 partially offset by decrease in revenue from clients in our healthcare industry group. The decrease in North America revenue for the nine months ended December 31, 2020 was primarily due to the decrease in revenue from clients in our healthcare industry group, partially offset by revenue from several tuck-in asset and business acquisitions closed in the fiscal year ended March 31, 2020.
In the three months ended December 31, 2020, our European revenue increased by 7.3%, or $4.0 million, to $59.2 million, or 17.1% of total revenue, from $55.2 million, or 16.5% of total revenue in the three months ended December 31, 2019. In the nine months ended December 31, 2020, our European revenue decreased by 6.6%, or $11.5 million, to $163.7 million, or 17.0% of total revenue, from $175.3 million, or 17.8% of total revenue in the nine months ended December 31, 2019. The increase in European revenue for the three months ended December 31, 2020 was primarily due to an increase in revenue from one of our large banking clients. The decrease in European revenue for the nine months ended December 31, 2020 was primarily due to a decline in revenue from one of our large banking clients, partially offset by an increase in our largest telecommunication client.
Our gross profit increased by $15.3 million to $114.0 million for the three months ended December 31, 2020, as compared to $98.7 million for the three months ended December 31, 2019. As a percentage of revenue, gross margin increased from 29.4% in the three months ended December 31, 2019 to 32.9% in the three months ended December 31, 2020. During the nine months ended December 31, 2020 and 2019, gross margin, as a percentage of revenue, was 27.6% and 27.8%, respectively. Our gross profit decreased by $6.3 million to $266.6 million for the nine months ended December 31, 2020 as compared to $272.9 million in the nine months ended December 31, 2019. The increase in gross profit during the three months ended December 31, 2020, as compared to the three months ended December 31, 2019, was primarily due to lower onsite effort, decrease in travel and related expense, as well as cost optimization programs with respect to our subcontractors implemented in the nine months ended December 31, 2020, partially offset by restoration of