fix: gather interesting years for stats accounting for published rfcs

[rjsparks]

FIxes #6772

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (e211dc5) 88.80% compared to head (e130a30) 88.80%.
Report is 2 commits behind head on main.

Files	Patch %	Lines
ietf/stats/views.py	85.71%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6776      +/-   ##
==========================================
- Coverage   88.80%   88.80%   -0.01%     
==========================================
  Files         285      285              
  Lines       40280    40283       +3     
==========================================
+ Hits        35771    35773       +2     
- Misses       4509     4510       +1     

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