A M P H E N O L C O R P O R A T I O N 2 0 0 4 A N N U A L R E P O R T  The Company maintains self-insurance programs for that portion of its health care and workers compensation costs not  covered by insurance. The Company also provides certain health care and life insurance benefits to certain eligible retirees through  postretirement benefit programs. The Company's share of the cost of such plans for most participants is fixed, and any increase in  the cost of such plans will be the responsibility of the retirees. The Company funds the benefit costs for such plans on a pay-as-you- go basis. Since the Company's obligation for postretirement medical plans is fixed and since the accumulated postretirement benefit  obligation ("APBO") and the net postretirement benefit expense are not material in relation to the Company's financial condition or  results of operations, we believe any change in medical costs from that estimated will not have a significant impact on the Company.  The discount rate used in determining the APBO at December 31, 2004 and 2003 was 5.75% and 6.15%, respectively. Summary  information on the Company's postretirement medical plans is as follows: At December 31, 2004, the Company was committed under operating leases which expire at various dates through 2010. Total rent expense under operating leases for the years 2004, 2003, and 2002 were $17,664, $18,650 and $16,007, respectively. Minimum lease payments under non-cancelable operating leases are as follows: Note 6—Leases  December 31,  2004  2003  Change in benefit obligation:  Benefit obligation at beginning of year  $12,752  $13,422   Service  cost  84 73  Interest  cost  776 799 Paid benefits and expenses  (2,060)  (1,733)   Actuarial  loss  1,552  191  Benefit obligation at end of year  $13,104  $12,752  Funded status  $(13,104) $(12,752) Unrecognized net actuarial loss  10,052  9,426  Unrecognized transition obligation  497  559  Accrued benefit cost  $ (2,555)  $ (2,767)  Year ended December 31,  2004  2003  2002 Components of net postretirement benefit cost:  Service cost  $ 84  $ 73  $ 71  Interest  cost  776  799  912 Amortization of transition obligation  62  62  62 Net amortization of actuarial losses  900  857  934 Net postretirement benefit cost  $1,822  $1,791  $1,979 2005  $16,546 2006  10,748 2007  6,934 2008  5,205 2009  3,922 Beyond 2009  5,353 Total minimum obligation  $48,708 51