How to show how many times the server was restarted on SQL Server?
Well, I think this can help:

you create a table, insert errorLog data inside this tabel and just select it:

create table ErrorLog ( 
LogDate datetime, 
ProcessInfo varchar(100),
Text varchar(max))

insert into errorlog  EXEC sp_readerrorlog 

select * from errorlog
    where Year(logdate)='2018'
    and text like '%Something%'


Or with a count:

select count(*) from errorlog
        where Year(logdate)='2018'
            and text like '%backup%'


We just need to use a string that is used during a server restart. Maybe '%Server name is%'. I can see this string on every restart.