2014 - 26,437 MQMs (on $2,822 MQD spend)
2015 - 19,754 MQMs
Net 25% loss for me.
And if I wasn't already Silver, it'd be 14,110 MQMs - a 47% drop.
Ouch.
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Edit - clearly I didn't catch that it was overall miles.
So, with that in mind:
2014 - 35,958 SkyMiles (including FO and AMEX bonuses)
2015 - 22,666 SkyMiles (including FO and AMEX bonuses) ** Not 100% clear since some flights were SkyTeam to Europe **
That's a 37% loss.
Also, I tend to rack up the most miles traveling for business. Even though I have a DL AMEX, I have to use my corporate card for all business travel (and have to book the cheapest economy fare). So this hits me twice on that front.
Ouch, indeed.