Makes sense to me. Looking at the 2016 Annual Report - we had 152 Airbii as of 31 Dec 2015. The 2017 Annual Report showed 158 one year later and says we might accept delivery of as many as 14 more Airbii between 2018 and 2021. Tuesday's release showed 166 Airbii.

Another possibility for the level number this year is the return of any leased aircraft being offset by induction of the used Airbii. I seem to recall we bought a bunch of 737s last year which were coming off lease, so our end of year numbers could turn out to be higher.