Premium revenue was $3,055.4 million for 2000, an increase of $644.1 million, or 23.7%, from $2,411.3 million in 1999. The increase was primarily due to an increase in premiums in the Guaranteed and Structured Financial Products Segment, including the sale of two significant single premium annuity contracts, and a $117.5 million increase, or 8.2%, in the Protection Segment primarily due to premiums on individual long-term care insurance products from the acquisition of a block of business.
Other revenue was $0.1 million in 1999, a decrease of $10.2 million, or 99.0%, from $10.3 million reported in 1998.
Segment after-tax operating income was $252.2 million in 2000, an increase of $63.5 million, or 33.6%, from $188.7 million in 1999. Non-traditional life insurance segment after-tax operating income increased $4.2 million, or 4.5%, primarily due to an increase in net investment income resulting from higher yields on higher net average invested assets. Traditional life insurance segment after-tax operating income increased $42.3 million, or 62.0%, primarily resulting from higher net investment income due to higher portfolio rates, lower operating expenses, and not repeating a $29.3 million charge, net of deferred acquisition costs, taken in 1999 for previously unreported claims associated with the demutualization. Individual long-term care insurance segment after-tax operating income increased $20.3 million, or 103.6%, resulting from an increase in net investment income due to the addition of the Fortis business and growth in average net invested assets. Group long-term care insurance segment after-tax operating income decreased by $0.3 million, or 4.3%.
Total benefits and expenses increased $34.0 million, or 4.0%, to $882.1 million in 1999 from $848.1 million in 1998. Benefits to policyholders increased $3.0 million, or 1.0%, primarily due to an increase in interest credited on fixed annuity account balances. Interest credited on fixed annuity account balances increased primarily due to higher average fixed annuity account balances of $4,862.2 million in 1999, as compared to $4,673.2 million in 1998. The increase in average fixed annuity account balances was partially offset by a decline in the average interest credited rate on fixed annuity account balances to 5.59% in 1999 from 5.96% in 1998. The average interest credited rate pattern is dependent upon the general trend of market interest rates, frequency of credited rate resets and business mix. Deferred fixed annuities' interest credited rates generally are reset annually on the policy anniversary. Other operating costs and expenses increased $24.4 million, or 4.8%, to $529.3 million in 1999 from $504.9 million in 1998. The increase was primarily due to our acquisition of the Essex Corporation and higher amortization of mutual fund deferred selling commissions, resulting from higher redemptions in 1999. These increases were partially offset by a decrease in operating expenses related to our mutual fund operations and annuities operations. Amortization of deferred policy acquisition costs increased $6.6 million, or 14.1%, to $53.4 million in 1999 from $46.8 million in 1998, primarily due to higher profits. The segment's effective tax rate was 34.3% and 33.6% in 1999 and 1998, respectively.
Segment after-tax operating income was $211.6 million in 2000, an increase of $9.9 million, or 4.9% from $201.7 million in 1999. Spread-based products' segment after-tax operating income increased $13.9 million, or 8.5%, to $178.3 million primarily due to higher investment spread as a result of an increase in average invested assets backing spread-based products. Fee-based products' segment after-tax operating income decreased $4.0 million, or 10.7%, to $37.3 million in 2000 from $37.7 million in 1999 primarily due to lower separate account GIC fees partially offset by increased gains from non-participating annuities.
The securities valuation office (SVO) of the National Association of Insurance Commissioners evaluates all public and private bonds purchased as investments by insurance companies. The SVO assigns one of six investment categories to each security it reviews. Category 1 is the highest quality rating, and Category 6 is the lowest. Categories 1 and 2 are the equivalent of investment grade debt as defined by rating agencies such as S&P and Moody's (i.e., BBB-/Baa3 or higher), while Categories 3-6 are the equivalent of below-investment grade securities. SVO ratings are reviewed and may be revised at least once a year.
(1) Total Company net investment income of $3,842.6 million is discussed in this Management's Discussion and Analysis, which includes net investment income of $3,251.0 million in the consolidated statements of income and $591.6 million in Note 6 -- Closed Block to the audited consolidated financial statements for the year ended December 31, 2000.