(4) Benefits to policyholders excludes amounts related to net realized investment gains credited to participating pension contractholders of $35.3 million, $79.1 million, $29.3 million, $22.3 million and $1.3 million for the years ended December 31, 1999, 1998, 1997, 1996 and 1995, respectively.
(8) Net realized investment gains have been reduced by: (1) amortization of deferred policy acquisition costs to the extent that such amortization results from realized gains and losses and (2) the portion of realized gains and losses credited to participating pension contractholder accounts. We believe presenting realized investment gains and losses in this format provides information useful in evaluating our operating performance. This presentation may not be comparable to presentations made by other insurers. Summarized below is a reconciliation of (a) net realized investment gains per the consolidated financial statements for the years ended December 31, 1999, 1998, 1997, 1996 and 1995, and (b) the adjustment made for net realized investment gains to calculate segment after-tax operating income for the years ended December 31, 1999, 1998 and 1997.
Management's Discussion and Analysis of Financial Condition and Results of Segment Operations
Ongoing Businesses. Premium revenue from ongoing businesses was $2,717.5 million for 1999, an increase of $519.6 million, or 23.6%, from $2,197.9 million in 1998. The increase was due to a $342.3 million increase in premiums in the Guaranteed and Structured Financial Products Segment, including the sale of one single premium annuity contract for $339.0 million, and a $58.1 million increase, or 26.6%, in the Protection Segment for premiums on individual long- term care insurance products.
Benefits to policyholders from ongoing businesses were $5,174.8 million for 1999, an increase of $1,034.0 million, or 25.0%, from $4,140.8 million in 1998. The increase was primarily due to a $373.9 million increase in benefits due to higher sales of single premium annuity contracts, a $345.5 million increase in benefits related to the compensation of group participating contractholders for assets transferred in conjunction with the formation of the corporate account, a $140.7 million increase in benefits on traditional life insurance products due to higher death benefits, including $61.7 million of reserves established for incurred but unreported deaths identified as a result of the policyholder demutualization mailing, a $113.2 million increase in benefits related to the settlement of a class action lawsuit involving individual life insurance policies sold from 1979 through 1996 and a $63.2 million increase in benefits on individual long-term care insurance products, resulting from higher sales.
Total revenues were $2,759.2 million in 1998, an increase of $127.4 million, or 4.8%, from $2,631.8 million in 1997. Premiums increased $8.4 million, or 0.6%, from 1997 primarily due to an increase in individual long-term care insurance premiums of $43.3 million, or 24.7%, partially offset by a decrease in traditional life insurance premiums of $38.0 million, or 3.5%. The decrease in traditional life insurance premiums was primarily due to $34.5 million of term insurance premiums, primarily related to policies issued from 1986 to 1995, which were ceded under a reinsurance contract entered into during 1998. Universal life and investment-type product charges increased $44.5 million, or 15.4%, to $333.3 million in 1998 from $288.8 million in 1997. Cost of insurance fees increased primarily due to growth in the average amount of variable life insurance in force, which increased 12.7% to $49,364.1 million in 1998 from $43,791.7 million in 1997. Fees earned on separate account products increased as a result of the strong stock market returns experienced during the year. Net investment income increased by $80.5 million, or 8.2%, compared to 1997, primarily reflecting an increase in the segment's invested assets. Other revenue decreased $6.0 million in 1998 primarily due to lower conversion fee income of $4.4 million resulting from the termination of our participation in the FEGLI Program.
Separate account assets are managed in accordance with specific investment contracts. We generally do not bear any investment risk on assets held in separate accounts, but rather receive investment management fees based on levels of assets under management, measured at fair value, as well as mortality fees, policy administration fees and surrender charges. Generally, assets held in separate accounts are not available to satisfy general account obligations.
. debt service coverage or cash flow ratios that fall below industry- specific thresholds;
The following table shows our commercial mortgage loan portfolio by loan size. Our commercial mortgage loan portfolio is highly diversified by borrower. As of December 31, 1999, 49.9% of the portfolio was comprised of mortgage loans with principal balances of less than $10 million. Consistent with our diverse base of business, our mortgage loans are originated through affiliated field offices across the country and through a national network of mortgage correspondents.
We use our internally developed Mortgage Investment Risk Analysis system to monitor the aggregate risk of our commercial mortgage loan portfolio. When a loan becomes more than 30 days delinquent, an assessment is made as to what course of action should be taken with the investment. In most instances, the loan is referred for foreclosure; however, in some circumstances we may decide that it is advantageous to restructure the loan. We will only restructure when we believe we will recapture lost income as markets improve.
Real Estate. We have recently completed a comprehensive strategic sales initiative, liquidating approximately 90% of our December 31, 1997 "non-home office" commercial real estate portfolio. Our current real estate holdings are predominantly comprised of our headquarters in Boston, Massachusetts.
The following table shows other invested assets carrying value and income by type. Our real estate joint ventures were disposed of in 1999 as part of our comprehensive real estate sale previously discussed.
Cash and Short-Term Investments. As of December 31, 1999, our short-term investments (including cash and cash-equivalents) totaled $1,984.8 million. Volatility in our annual short-term investment income reflects swings in our cash balances, as well as changes in short-term interest rates. As a general policy, we aim to minimize the opportunity cost of holding excess cash and short-term investments, while balancing our need to meet obligations to our policyholders and creditors, as well as to settle investment transactions. We invest short-term funds in commercial paper, certificates of deposit and other short-term instruments, subject to investment guidelines regarding issuer concentration, quality and maturity. We also have an active securities-lending program.