IDENTIFIED INTANGIBLE ASSETS AND LIABILITIES

Our identified intangible assets (acquired in-place and above and below-market leases) and liabilities (acquired below-market leases), net of accumulated amortization were $33.3 million and $153.0 million as of March 31, 2016, respectively, and $34.0 million and $154.9 million as of December 31, 2015, respectively.

Amortization of acquired below-market leases, net of acquired above-market leases resulted in additional rental income of $1.9 million and $2.0 million for the quarters ended March 31, 2016 and 2015, respectively. Estimated annual amortization of acquired below-market leases, net of acquired above-market leases for each of the five succeeding years commencing January 1, 2017 is as follows:



(Amounts in thousands)
2017	$	7,448
2018	7,227
2019	7,204
2020	7,211
2021	7,182

Amortization of acquired in-place leases and customer relationships resulted in additional depreciation and amortization expense of $0.4 million for each of the quarters ended March 31, 2016 and 2015. Estimated annual amortization of these identified intangible assets for each of the five succeeding years commencing January 1, 2017 is as follows:



(Amounts in thousands)
2017	$	1,523
2018	1,341
2019	1,220
2020	1,177
2021	1,078

Certain of the shopping centers were acquired subject to ground leases or ground and building leases. Amortization of these acquired below-market leases resulted in additional rent expense of $0.2 million for each of the quarters ended March 31, 2016 and 2015. Estimated annual amortization of these below-market leases for each of the five succeeding years commencing January 1, 2017 is as follows:



(Amounts in thousands)
2017	$	972
2018	972
2019	972
2020	972
2021	622