Absolutely not a "best practice" because of the way Dictionary is used.
Since a while, .Net take care of the order of insertion, but it is not specify and can change at any time.

A dictionary is meaned to store a relation between keys and values, not the order of keys.

The usage of anonymous class or Tuple would be far better.

The rest is perfect.

what am I even looking at
this guy is dangerous guys keep him away from society

Creative use of Aggregate for text formatting.

Just a remark to always benchmark your code to make this statement. As newer releases of .Net Core also Regex gets faster and faster.
So better stay maintainable and readable and let the performance guys do their work
References:

• https://devblogs.microsoft.com/dotnet/regex-performance-improvements-in-net-5/
• https://devblogs.microsoft.com/dotnet/regular-expression-improvements-in-dotnet-7/
• https://devblogs.microsoft.com/dotnet/performance-improvements-in-net-8/#searchvalues which is/will be used by Regex under the hood

I like the way you calculated years and so on.

There is actually no difference as these functions are evaluated lazily.

how to view hidden comment?

Because none of the tests check for leading apostrophes