History

[paul]

There's only the latest available data for let's say cellular phones in use in a particular country. "Poland cellular phones 2005" does not work, there's only a 2009 estimate. Why is that?

[Macen]

It may not have been recorded in 2005,

Just like how we dont have the number of teapots that were in china 1000 years ago,

[Arvin]

The data was recorded and published in the CIA's The World Factbook.

2005 CIA World Factbook, Poland, Telephones - mobile cellular: 17.401 million (2003)
2007 CIA World Factbook, Poland, Telephones - mobile cellular: 29.166 million (2005)

[Macen]

The data was recorded and published in the CIA's The World Factbook.

2005 CIA World Factbook, Poland, Telephones - mobile cellular: 17.401 million (2003)
2007 CIA World Factbook, Poland, Telephones - mobile cellular: 29.166 million (2005)

The data then probably needs to be inputted by a curator.

[Deepze]

Take into account the enormity of the WolframAlpha project.

I am guessing that current statistics were prioritized over historical data so that other topics could be curated, if there is an initial entry in the dataset I would expect the appearance of more data once the dataset is revisited.