|TRIVAGO N.V. filed this Form 20-F on 03/06/2018|
in our marketplace, and in particular, to gain insight into how our advertisers manage their advertising campaigns. Generally, the higher the potential booking value generated by a qualified referral and the more competitive the bidding, the more an advertiser is willing to bid for a hotel advertisement on our marketplace. This means that the levels of advertisers' CPC bids reflect their view of the likelihood that each click on an offer will result in a booking by a user. Reflecting these dynamics, we have observed that advertisers tend to adjust their CPC bidding based on the relative strengthening or weakening of the euro as compared to the local functional currency in which the booking with our advertisers is denominated, even though we invoice the majority of our advertisers in euro and have relatively little direct foreign currency translation with respect to our revenue.
RPQR is a key financial metric that describes the quality of our referrals, the efficiency of our marketplace and, as a consequence, how effectively we monetize the referrals we provide our advertisers. Furthermore, we use RPQR to help us detect and analyze changes in market dynamics. For the years ended December 31, 2015, 2016 and 2017, RPQR was €1.46, €1.39 and €1.40, respectively.
The following table sets forth the RPQR for our reportable segments for the periods indicated (based on Referral Revenue):
The following tables set forth the percentage change year-on-year in each of the components of RPQR for our reportable segments for the years indicated. Percentages calculated below are based on the unrounded amounts and therefore may not recalculate on a rounded basis.