Activity in capitalized mortgage servicing rights and related valuation allowance during 2001, 2000 and 1999 are as follows (in thousands): : Capitalized Mortgage Servicing Rights -Valuation Hedging Purchased. Originated Total Allowance » (Gain)/Loss Net Balance at December 31, 1998 $65,607 $26,101 $ 91,708 $ = $(22,484) $69,224 Additions. 16,099 11,483 27,582 _ _ 27.582 Amortization expense (11,297) (4,266) (15,563) - 734 (14,829) Realized hedge losses - ~ - = 28,293 28,293 Unrealized hedge losses _ _ = - 3,864 3,864 Balance at December 31,1999 70,409 33,318 103,727 - 10,407 114,134 Additions 2,449 11,267 13,716 = - 13,716 Amortization expense (9,497) (4,260) (13,757) = (1.445) (15,202) Provision for impairment = _ = (2,900) = (2,900) - 4,389 4,389 Realized hedge losses - _ ~ Unrealized hedge gains = (3,346) (3,346) a a = Balance at December 31,2000 63,361 40,325 103,686 (2,900) 10,005 110,791 Additions 4,400 22,695 27,095 - - 27,095 Amortization expense (12,705) (9,409) (22,114) _ (1,425) (23,539) z (15,551) - (15,551) Provision for impairment = - Balance at December 31, 2001 $55,056 $53,611 $108,667 $(18,451) $8,580 . $ 98,796 Estimated fair value of mortgage servicing rights at: December 31, 1999! $83,279 $37,547 $120,826 $120,826 December 31, 2000! $74,400 $42,125 $116,525 $116,525 December 31, 2001! $53,174 $46,789 $99,963 $ 99,963 < 6.50% 6.50% - 7.49%. 7.50% = 8.49% => 8.50% Total‘ Cost less accumulated amortization $ 17,370 $..63,181 $. 25,882 $2,234 $108,667 Deferred hedge losses - 7,583 997 ~ 8,580 Adjusted cost $ 17,370 $ 70,764 $26,879 $2,234 $117,247 Fair value $ 15.914 $62,097 $ 19,286 $.:2,666 $.99,963 Impairment! $ 2.009 $ 8,689 $7,593 $ 160 $ 18,451 Outstanding principal of loans serviced! $884,228 $3,746,212 $1,453,738 $191,923 $6,276,101 Excludes approximately, $9 million, $8 million and $5 million at December 31, 1999, 2000 and 2001, respectively, of loan servicing rights on mortgage loans originated prior to the adoption of FAS.122. Fair value is determined by discounting the projected net cash flows, Significant assumptions are: Discount rate - Risk adjusted rates by loan product, ranging from 9.00% to 20.00%. Stratification of the mortgage loan servicing portfolio, outstanding principal of loans serviced, and related hedging information by interest rate at December 31, 2001 follows (in thousands): Prepayment rate — Annual prepayment estimates ranging from 7.50% to 68.52% from an independent reporting source based upon loan interest rate, original term and loan type. Loan servicing costs — $40 to $50 per loan based upon loan type. Exelüdes outstanding principal of $370 million for loans serviced by BOk for which there are no capitalized mortgage servicing rights. Impairment is determined by both an interest rate and loan type stratification. The aggregate amounts of time deposits in denominations of $100,000 or: more at December 31, 2001 and 2000 were $1.6 billion and $1.4 billion, respectively. Time deposit maturities are as follows: 2002 - ‚me dep ‚ar ru $L8 billion, 2003 - $186 million, 2004 ~ $252 million, 2005 — $38 million, 2006 — $529 million, and $345 thousand thereafter. : . . Interest expense on time deposits during 2001 and 2000 was reduced by net income from interest rate swaps of $3.1 million and $876 thousand, respectively. (9) Deposits 2001 2000 1999 ; ; Transaction deposit 55.01 46,510 Sains va 350m SA Time: , ” , Certificates of deposits under $100.000 61,626 56.570 41.418 Certificates of deposits $100,000 and over 81,524 81.721 49.166 Other time deposits 13,063 12,236 10,556 Total time 156,213 150,527 101,140 nee Total $208,387  $208,249 .$150,621