Which tables can be safely truncated?

What tables can be safely truncated? Our database size is at 12.9 gb

I ran following query to figure out table sizes:

SELECT
t.Name                                       AS TableName,
s.Name                                       AS SchemaName,
p.Rows                                       AS RowCounts,
SUM(a.total_pages) * 8                       AS TotalSpaceKB,
(SUM(a.total_pages) * 8/1024)                AS TotalSpaceMB,
(SUM(a.total_pages) * 8/(1024*1024))                AS TotalSpaceGB,
SUM(a.used_pages) * 8                        AS UsedSpaceKB,
(SUM(a.total_pages) - SUM(a.used_pages)) * 8 AS UnusedSpaceKB
FROM
sys.tables t
INNER JOIN sys.indexes i ON t.object_id = i.object_id
INNER JOIN sys.partitions p ON i.object_id = p.object_id AND i.index_id = p.index_id
INNER JOIN sys.allocation_units a ON p.partition_id = a.container_id
LEFT OUTER JOIN sys.schemas s ON t.schema_id = s.schema_id
WHERE
t.Name NOT LIKE 'dt%'
AND t.is_ms_shipped = 0
AND i.object_id > 255
GROUP BY
t.Name, s.Name, p.Rows
ORDER BY
TotalSpaceMB desc;

The tables with most data are:

TableName                   SchemaName  RowCounts   TotalSpaceKB    TotalSpaceMB    UsedSpaceKB
Staging_Task                dbo         157843      10775944        10523           10761864
CMS_ObjectVersionHistory    dbo         2550        677496          661             670600
OM_Activity                 dbo         472070      517120          505             382720
Analytics_HourHits          dbo         2054845     340704          332             312928
CMS_VersionHistory          dbo         20132       258808          252             247800
Analytics_DayHits           dbo         1418667     227808          222             198792
CMS_Relationship            dbo         1143306     210128          205             163568
OM_Contact                  dbo         184104      149296          145             119160
Analytics_WeekHits          dbo         652004      113632          110             89528
Analytics_MonthHits         dbo         260910      47904           46              35800
Analytics_Statistics        dbo         76595       22368           21              16672
Analytics_YearHits          dbo         101668      18528           18              13712
CMS_Document                dbo         5170        17616           17              12440
Media_File                  dbo         7899        17048           16              12576