How to enable the developer dashboard in Sharepoint 2013 in Powershell

The following options for the Developer Dashboard:
On
SharePoint 2010: The Developer Dashboard will always be rendered at the bottom of each page
SharePoint 2013: The Developer Dashboard icon will always be displayed at the top right corner.
It will not be appended to each page. Off
SharePoint 2010 & 2013: The Developer Dashboard will not be available
OnDemand
SharePoint 2010: The Developer Dashboard will only be appended to
a page after clicking on the icon in the ribbon
SharePoint 2013: This mode is not available in 2013 since it reflects the behavior of On now

$svc = [Microsoft.SharePoint.Administration.SPWebService]::ContentService

$dds = $svc.DeveloperDashboardSettings

$dds.DisplayLevel = "On"

$dds.Update()