At my organization I am the only fulltime DBA, responsible for over 50 instances and 700+ SQL Server databases. Thus, I'm on call 24x7x365 (that includes vacations). Prior to being the DBA, I was one of the developers and we had no DBA. Since I was fixing most of the database issues when they happened anyway, I asked to be the fulltime DBA. I used to get calls and pages after hours 4-5 times a week. After 4 years of being the DBA, I get actual phone calls about database issues 1-2 times a year, and pages from automated monitoring I setup 4-5 times a month.
The biggest reason for the downturn is getting the developers to use source code control and automating development environment refreshes for them so they're coding in an environment that matches the production environment they're going to deploy to. They catch a lot more of their errors before the code gets to production and they write a lot better code now. Most of my pages now are warnings about impending disk space issues.