The library charges $50 a year for individual subscribers.
Paper journals are now generally made available in electronic form as well, both to individual subscribers, and to libraries.
For a monthly fee, individual subscribers order the programs and services that suit them.
But the company says it has 29,000 individual subscribers and 1,300 more corporate and academic accounts.
But they insisted there was no way the hackers could get access to the credit information on individual subscribers.
Until 1988 all individual subscribers and employees of businesses that employed no more than 50 people were charged the broad community rate.
Quite apart from all these individual subscribers were those wishing to promote the work.
The project was widely supported in the United States by some 50,000 individual subscribers.
The company's poor financial position has led to five rate increases in the last four years that have fallen heavily on individual subscribers.
When published, copies were available to individual subscribers by regular mail.