I had a bit same case in my project. When I investigated how Azure Search works underhood I found that string types all times converted to Contains query in Azure Search. You can see that if taking a look into Search.log for your environment.
The same issue with the StartsWith() function and etc. check this link:
In your case I see some scenarios to resolving this issue:
- Make a computed/change type of field
year. That can beint. (Equals for integer types works well) - Switch to Solr (it will take 1-day max but will save a lot of time with Search work). Anyway, the azure search will be deprecated in the next version of Sitecore.
- Use straight requests to Azure Search instead of Sitecore LINQ provider. There exists an Equals function that can be used. (take a lot of time for rewriting and hard to support solution like this)
- Take a look at the
Wildcard()LINQ function that allows using Search Engine syntaxis for field requests. Probably it will help too.
My experience with Azure Search was a nightmare till we didn't switch to Solr Engine. Because they're a lot of limitations.