Table:
|  |  |  | Year Ended December 31, |  |  |
| --- | --- | --- | --- | --- | --- |
|  | 2019 | % Change | 2018 | % Change | 2017 |
|  |  |  | (in thousands, except percentage data) |  |  |
| Net revenue | $711,391 | (7.7)% | $771,060 | 0.4% | $768,261 |
| Percentage of net revenue | 71.2% |  | 72.8% |  | 73.9% |
| Contribution income | $67,775 | (29.7)% | $96,340 | 14.9% | $83,870 |
| Contribution margin | 9.5% |  | 12.5% |  | 10.9% |
Paragraphs:
2019 vs 2018
Net revenue in Connected Home segment decreased for the year ended December 31, 2019 compared to the prior year. Net revenue from service provider customers fell $27.8 million compared with the prior year. In addition, the North American home WiFi market contracted in fiscal 2019 affecting net revenue from non-service provider customers. The lower revenue was primarily due to declined net revenue of our home wireless, mobile and broadband modem and gateway products. Within home wireless, we experienced declines in net revenue from AC router products, WiFi mesh systems and extenders, partially offset by net revenue generated from the introduction of WiFi 6 routers. On a geographic basis, we experience net revenue declines across all three regions.
Contribution income decreased for the year ended December 31, 2019 compared to the prior year, primarily due to lower net revenue and lower gross margin attainment. Contribution margin decreased for the year ended December 31, 2019 compare to the prior year primarily due to higher product acquisition costs resulting from the burden of Section 301 tariffs and inefficiencies associated with commencing manufacturing in new locations, increased channel promotion activities and foreign exchange headwinds due to the strengthening of the U.S. dollar.
2018 vs 2017
2018 vs 2017 Connected Home segment net revenue increased for the year ended December 31, 2018 compared to the prior year. The increase in Connected Home net revenue was primarily due to home wireless and broadband modem and modem gateway products, partially offset by decreased net revenue from mobile products. The growth in home wireless was experienced across both service provider and non-service provider channels, while the increase in broadband and gateway related solely to non-service provider customers. In total, net revenue from service provider customers fell $33.5 million compared to the prior year period. Geographically, net revenue increased in Americas and EMEA, but decreased in APAC.
Contribution income increased for the year ended December 31, 2018 compared to the prior year, primarily due to higher net revenue and gross margin attainment, mainly due to favorable product mix and lower warranty expense, partially offset by higher operating expenses as a proportion of net revenue.
Question:
In which year is the percentage of net revenue the lowest?
Answer: Because 71.2% < 72.8% < 73.9%, the answer is: 2019.