These may be a little outdated, but this may give you some idea.
I got this from a website:http://www.cybercollege.com/tvp009.htm
Although by early 2001, almost a million high-definition sets had been sold in the U.S., this number represents only a fraction of the total sets in use.
And this from another: http://www.broadcastpapers.com/editing/avidhdtv02.htm
99% of the world's viewers are still watching analog NTSC and PAL. There are an estimated 250 million NTSC television sets in the US alone, and that won't change overnight. According to the Consumer Electronics Manufacturers Association (CEMA), 13,176 HD-ready TV sets were sold to dealers in the US in 1998, primarily for the professional market. This compares with 27,000,000 conventional television sets sold in the same period.
The adoption of HDTV and SDTV will increase as the cost/benefit ratio improves - which ultimately means more content and less expensive TV sets. HDTV programming in the 1999/2000 season is expected to be less than 5% of the broadcast day but at least one HDTV signal will reach about 25% of the viewing public. HDTV will, however, grow at an increasing rate. SDTV, especially widescreen SDTV, will likely be adopted more quickly. SDTV is less expensive and has more immediate benefits to consumers. These include improved image and audio quality, a wider aspect ratio and digital multicasting - the simultaneous broadcasting of multiple channels using the bandwidth of a single traditional channel.
The growth of DTV is inevitable. HDTV and SDTV enhance the viewer's experience and represent exciting new opportunities for content producers. Furthermore, HDTV masters ensure the archival value of content. We are moving to a digital world - from acquisition to consumption. The debate is about the length of that transition, not whether or not it will occur. The transition initiates the dawn of a multi-format world. Multi-format distribution ensures the maximum number of viewers, and reaching viewers drives advertising dollars, subscription revenues, and the very business of broadcasting. HDTV and SDTV adoption will continue, but 601 delivery will be critical to reaching the mass market and driving the largest portion of revenue streams for years to come. In this context, HDTV is not a solution unto itself, but an important element in multi-format distribution.
But multi-format distribution is only one part of the coming revolution. The challenge is not simply to create compelling content and distribute it to the widest possible audience. Content must also be made geographically and demographically relevant in as many ways as possible. Gone are the days of creating a single version of a program. Now we create the network version, the syndicated version, the cable version, the domestic and international versions, the airline version, and so on. The same is true in the spot market. :60, :30, :15 and :10 cuts are all created from the original masters as part of the broadcast strategy for a high-end spot. A national or regional commercial is no longer produced as a single generic spot. Now several local versions are the requirement. For example, a commercial for the Midwest is now a Chicago version, a Detroit version and a St. Louis version. The deadline is still the same, but three or four spots now have to be created in the time that it used to take to produce one. Repurposing content for different programming is yet another form of versioning. This trend will intensify as new post-production solutions enable us to create multiple versions with greater ease and efficiency.
In this new multi-format, multi-version world, the television post-production process becomes considerably more complex. Multiple DTV, PAL and NTSC masters in 16:9, 4:3 and letterbox aspect ratios, along with multiple versions for different markets, result in a far more complex fulfillment task. The solution is not simply narrative offline editing systems and HD conforming stations. The solution must provide an economical and efficient means to produce all of the necessary formats and versions