The 12% growth in Sky Miles redemptions appear to be compared to Q1 of last year from my understanding of the conference call today. They attribute the rollout of "SkyMiles as currency" to mobile as the driving factor. People are probably more impulsive to spend those miles on an offer on their phone than logging in via web browser. Half of upgrades using miles happened on mobile. Mobile is now 20-25% of their direct bookings.
Much of what they say regarding AMEX revenue is annualized projections. One analyst pressed them how they can project a doubling of AMEX revenue by 2023 and wanted more transparency behind that. AMEX and DL have a confidentiality agreement regarding details of their agreement, although both are public companies and must post their respective revenue and expenses, they don't give breakdowns and numbers of AMEX members, average spend, etc in that partnership.
Joseph DeNardi --
Stifel, Nicolaus & Co. -- Analyst
Yes. Good morning. Ed, in 2018, you guys received $3.5 billion in cash from the selling miles and reported about $1.5 billion in marketing fee. You're on track for $2 billion in 2020. If you can get to $7 billion in 2023, you'll be doing $3 billion to $4 billion in marketing fee. How could you possibly not break that out as a separate business unit? I'm not talking about spinning it or selling it, just segmenting it out. What are your thoughts there?
Ed Bastian --
Chief Executive Officer
Well, my thoughts are as a good problem to worry about, Joe. We are -- first of all, we are pleased and thrilled with the new renewal. AmEx is an awesome partner and our two brands line up so well strategically and with our customers and our people. As we grow our loyalty program, you're right, there will be a question of disclosure in terms of providing better insight from an ownership perspective and a governance perspective into the drivers of our profitability into the future and whether that's in a segment or whatever disclosure format, I am not sure what it will take, but it's something that we've been giving greater disclosure to, as you know, and we'll continue to consider that.
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The AMEX component is not insignificant, and those 50% margins can really help ease the pain of a quarter when there might be a little pressure on flight operating margins.
Since nobody posted the link yet, here is Ed on CNBC this morning...
https://www.cnbc.com/2019/04/10/delt...-earnings.html
Transcript of the Conference Call:
https://www.fool.com/earnings/call-t...gs-call-t.aspx
I am a very happy shareholder this quarter and it's nice to see their performance be reflected in the stock price, since in 2018 it seemed that UAL got all of the love. But the street is fickle and once it became well-known that DAL did not have the MAX, it became the darling of the major airline stocks again, and then this quarter turbocharged that.