2000 marked a tremendous year of growth, said Jim Robbins, President and Chief Executive Officer. We gained unprecedented ground with our advanced telecommunications services and achieved solid financial and operational results.
We ended the year on a strong note with 14% pro forma operating cash flow (OCF) growth for the fourth quarter, resulting in 10% pro forma OCF growth for the year, said Robbins. Operationally, we continued to demonstrate steady and consistent growth in our core product offering, resulting in 1.8% pro forma basic customer growth.
Total revenues for the twelve months ended December 31, 2000 were $3,573.3 million, a 12% increase over revenues of $3,199.7 million for the twelve months ended December 31, 1999. Total residential revenues for the twelve months ended December 31, 2000 increased 9% to $3,122.8 million compared to the same period in 1999. Basic customers were 6,193,317, a 1.8% increase over December 31, 1999 after adjusting for the above transactions.
Residential video revenues include complete basic, premium service and pay-per-view revenues. Complete basic revenues for the twelve months ended December 31, 2000 increased 8% over 1999 primarily due to basic and digital customer growth and rate increases implemented primarily in the first quarter of 2000 resulting from increased programming costs and inflation, as well as increased channel availability. The increase in complete basic revenues was offset by a decrease in pay-per-view revenues resulting from fewer national boxing events.
Residential data and telephony revenues for the twelve months ended December 31, 2000 increased to $138.4 million and $106.1 million, respectively, from $60.1 million and $45.0 million, respectively, due to customer growth. Commercial revenues for the twelve months ended December 31, 2000 increased to $97.8 million from $52.0 million due to growth in both high-speed data and telephony customers.
Advertising revenues increased 21% to $352.7 million due to continued growth in local and national advertising sales.