Create incrementing number for Parent

I am attempting to create a special format incrementing number but I am not sure where to begin.
In my parent record I have a field called "Paving bid number" which I need to increment as 20-100, 20-101, 20-102 ect.
This is based on the year 2020 and the increments start with 100 for the first record of the year with the 20 changing to 21 next year and so on. I have noticed some people use a table to define the years 2020, 2021, 2022 ect.

I am not sure where to start with these type of parameters any help is appreciated.

Thanks
Michael

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Michael
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