You are correct, the web page was discontinued. It used to be located here: http://www.microsoft.com/learning/mcp/certified.mspx
Here is the official answer from Microsoft:
Microsoft Learning decided that presenting the number of people for each certification was of diminishing value given the sheer size of the numbers for each certification. In some cases it was at risk undermining the value of the certification as people felt like too many people had it
Now, you could use the Internet Archive WayBack Machine to look at a historical version of the web page:
http://web.archive.org/web/20090418194116/http://www.microsoft.com/learning/mcp/certified.mspx
Ahh, the memories...