sys.dm_os_wait_stats

Sometimes i had problem with slow working of sql server.After reading some article i find about running sys.dm_os_wait_stats. In my sql server i ran query 

select * fromsys.dm_os_wait_stats
order by wait_time_ms desc

The top 20 rows of output is as shown below

So is this a normal condition or do i have any performance problem with sql server.

Please help me on this.