I'm currently using =IF(B1=B2,C1,MAX($C$1:C1)+1) in column C and it works fine to establish a sequential numbering, but not sure how to adjust for a new year.
Data Range
<tbody>
A
B
C
1
Year
Team
Series
2
2018
Team1
1
3
2018
Team1
1
4
2018
Team1
1
5
2018
Team2...