The following table presents changes in mortgage servicing rights for the periods presented:


(dollars in thousands)	Mortgage Servicing Rights
Balance, January 1, 2020	$	14,718
Additions	174
Amortization	(1,547)
Balance, March 31, 2020	$	13,345

Balance, January 1, 2021	$	11,865
Additions	461
Amortization	(1,232)
Balance, March 31, 2021	$	11,094

Income generated as the result of new mortgage servicing rights is reported as gains on sales of loans and totaled $0.5 million for the three months ended March 31, 2021 compared to $0.2 million for the three months ended March 31, 2020.

Amortization of mortgage servicing rights totaled $1.2 million for the three months ended March 31, 2021 compared to $1.5 million for the three months ended March 31, 2020.

The following tables present the fair market value and key assumptions used in determining the fair market value of our mortgage servicing rights:


	Three Months Ended			Three Months Ended
(dollars in thousands)	March 31, 2021			March 31, 2020
Fair market value, beginning of period	$	12,003		$	15,820
Fair market value, end of period	11,673			13,525
Weighted average discount rate	9.6		%	9.5		%
Weighted average prepayment speed assumption	17.5		%	16.1		%

The gross carrying value and accumulated amortization related to our mortgage servicing rights are presented below:


	March 31, 2021						December 31, 2020
(dollars in thousands)	Gross Carrying Value		Accumulated Amortization		Net Carrying Value		Gross Carrying Value		Accumulated Amortization		Net Carrying Value

Mortgage servicing rights	$	71,370	$	(60,276)	$	11,094	$	70,909	$	(59,044)	$	11,865

Based on the mortgage servicing rights held as of March 31, 2021, estimated amortization expense for the remainder of fiscal year 2021, the next five succeeding fiscal years and all years thereafter are as follows:


(dollars in thousands)
Year Ending December 31,
2021 (remainder)	$	3,642
2022	3,584
2023	2,918
2024	950
2025	—
2026	—
Thereafter	—
Total	$	11,094