24/264 Music Group, and Merlin, makes up the majority of music consumed on our Service. For the year ended December 31, 2017, this content accounted for approximately 87% of streams. Our business may be adversely affected if our access to music is limited or delayed because of deterioration in our relationships with one or more of these rights holders or if they choose not to license to us for any other reason. Rights holders also may attempt to take advantage of their market power to seek onerous financial terms from us, which could have a material adverse effect on our financial condition and results of operations. Even if we are able to secure rights to sound recordings from record labels and other copyright owners, artists and/or artist groups may object and may exert public or private pressure on third parties to discontinue licensing rights to us, hold back content from us, or increase royalty rates. As a result, our ability to continue to license rights to sound recordings is subject to convincing a broad range of stakeholders of the value and quality of our Service. To the extent that we are unable to license a large amount of content or the content of certain popular artists, our business, operating results, and financial condition could be materially harmed. We have incurred significant operating losses in the past, and we may not be able to generate sufficient revenue to be profitable, or to generate positive cash flow on a sustained basis. In addition, our revenue growth rate may decline. Since our inception in April 2006, we have incurred significant operating losses and as of December 31, 2017, had an accumulated deficit of €(2,427) million. For the years ended December 31, 2015, 2016, and 2017, our operating losses were €(235) million, €(349) million, and €(378) million, respectively. We have incurred significant costs to license content and continue to pay royalties to music labels, publishers, and other copyright owners for such content. We cannot assure you that we will generate sufficient revenue from the sale of our Premium Service and advertising for our Ad­Supported Service to offset the cost of our content and these royalty expenses. If we cannot successfully earn revenue at a rate that exceeds the operational costs, including royalty expenses, associated with our Service, we will not be able to achieve or sustain profitability or generate positive cash flow on a sustained basis. From 2015 to 2016, our total revenue grew from €1,940 million to €2,952 million, and from 2016 to 2017, our total revenue grew to €4,090 million, which represents a CAGR of 45%. We expect that, in the future, our revenue growth rate may decline because of a variety of factors, including increased competition and the maturation of our business. We cannot assure you that our revenue will continue to grow or will not decline. You should not consider our historical revenue growth or operating expenses as indicative of our future performance. If our revenue growth rate declines or our operating expenses exceed our expectations, our financial performance will be adversely affected. Additionally, we also expect our costs to increase in future periods, which could negatively affect our future operating results and ability to achieve profitability. We expect to continue to expend substantial financial and other resources on: • securing top quality audio and video content from leading music labels, distributors, aggregators, as well as the publishing right to the underlying musical compositions; • creating new forms of original content; • our technology infrastructure, including website architecture, development tools, scalability, availability, performance, security, and disaster recovery measures; • research and development, including investments in our research and development team and the development of new features; • sales and marketing, including a significant expansion of our field sales organization; 17