Number one vs the number one

[Alexey86]

1. "Denmark is no longer the number one in Europe on human rights, but at the bottom of the table.
https://www.theguardian.com/world/2...ts-activist-lisbeth-zornig-people-trafficking

2. VW is the number one in the latter market.
https://www.theguardian.com/business/2009/dec/09/volkswagen-stake-suzuki-motor-porsche

3. Wheat is number one in acreage.
https://agrifoodecon.springeropen.com/articles/10.1186/s40100-016-0055-8

4. “Today, America is number one in oil and gas,” he said. “America is number one in wind power.
https://www.huffpost.com/entry/the-climate-post-obama-ta_b_6526668


Why is the used in (1-2), but not in (3-4)?

 

[Tarheel]

It seems that "the" could have been omitted in the first one. The second one too. I would probably put it down to personal preference.