A survey was created with the non-anonymize option set. The responses are stored with a submitdate of 1980-01-01.

mysql> select * from lime_surveys where sid = 856921 \G
1. row
sid: 856921
owner_id: 35
admin: CCC
active: Y
expires: 2014-09-10 00:00:00
startdate: 2014-09-01 00:00:00
adminemail: admin@mycompany.com
anonymized: N
faxto:
format: G
savetimings: N
template: basic_mycompany1
language: en
additional_languages: zh-Hans
datestamp: N
usecookie: N
allowregister: N
allowsave: N
autonumber_start: 7
autoredirect: N
allowprev: N
printanswers: N
ipaddr: N
refurl: N
datecreated: 2014-08-27
publicstatistics: N
publicgraphs: N
listpublic: N
htmlemail: Y
tokenanswerspersistence: N
assessments: N
usecaptcha: D
usetokens: N
bounce_email: someone@mycompany.com
attributedescriptions: NULL
emailresponseto:
emailnotificationto:
tokenlength: 15
showxquestions: Y
showgroupinfo: B
shownoanswer: Y
showqnumcode: X
bouncetime: NULL
bounceprocessing: N
bounceaccounttype: NULL
bounceaccounthost: NULL
bounceaccountpass: NULL
bounceaccountencryption: NULL
bounceaccountuser: NULL
showwelcome: Y
showprogress: Y
navigationdelay: 0
nokeyboard: N
alloweditaftercompletion: N
googleanalyticsstyle: 0
googleanalyticsapikey:
sendconfirmation: Y
questionindex: 0
1 row in set (0.00 sec)

mysql> select submitdate,count() from lime_survey_856921 group by submitdate;
+---------------------+----------+
| submitdate | count() |
+---------------------+----------+
| NULL | 32 |
| 1980-01-01 00:00:00 | 149 |
+---------------------+----------+
2 rows in set (0.00 sec)