Complex sentence: Steady growth continued through the 1980s, but a combination of factors led to rapid growth after 1988, and by April 1993 the FidoNet nodelist contained over 20,000 systems.
Split into simpler sentences: Steady growth continued through the 1980s, but a combination of factors led to rapid growth after 1988. By April 1993 the FidoNet nodelist contained over 20,000 systems.