diff --git a/app/api/managers.py b/app/api/managers.py
new file mode 100644
index 00000000..7aa8dd48
--- /dev/null
+++ b/app/api/managers.py
@@ -0,0 +1,33 @@
+from collections import Counter
+
+from django.db.models import Manager, Count
+
+
+class AnnotationManager(Manager):
+
+    def get_label_per_data(self, project):
+        label_count = Counter()
+        user_count = Counter()
+        docs = project.documents.all()
+        annotations = self.filter(document_id__in=docs.all())
+
+        for d in annotations.values('label__text', 'user__username').annotate(Count('label'), Count('user')):
+            label_count[d['label__text']] += d['label__count']
+            user_count[d['user__username']] += d['user__count']
+
+        return label_count, user_count
+
+
+class Seq2seqAnnotationManager(Manager):
+
+    def get_label_per_data(self, project):
+        label_count = Counter()
+        user_count = Counter()
+        docs = project.documents.all()
+        annotations = self.filter(document_id__in=docs.all())
+
+        for d in annotations.values('text', 'user__username').annotate(Count('text'), Count('user')):
+            label_count[d['text']] += d['text__count']
+            user_count[d['user__username']] += d['user__count']
+
+        return label_count, user_count
diff --git a/app/api/models.py b/app/api/models.py
index 573d7661..93307487 100644
--- a/app/api/models.py
+++ b/app/api/models.py
@@ -7,6 +7,8 @@ from django.contrib.staticfiles.storage import staticfiles_storage
 from django.core.exceptions import ValidationError
 from polymorphic.models import PolymorphicModel
 
+from .managers import AnnotationManager, Seq2seqAnnotationManager
+
 DOCUMENT_CLASSIFICATION = 'DocumentClassification'
 SEQUENCE_LABELING = 'SequenceLabeling'
 SEQ2SEQ = 'Seq2seq'
@@ -192,6 +194,8 @@ class Document(models.Model):
 
 
 class Annotation(models.Model):
+    objects = AnnotationManager()
+
     prob = models.FloatField(default=0.0)
     manual = models.BooleanField(default=False)
     user = models.ForeignKey(User, on_delete=models.CASCADE)
@@ -225,6 +229,9 @@ class SequenceAnnotation(Annotation):
 
 
 class Seq2seqAnnotation(Annotation):
+    # Override AnnotationManager for custom functionality
+    objects = Seq2seqAnnotationManager()
+
     document = models.ForeignKey(Document, related_name='seq2seq_annotations', on_delete=models.CASCADE)
     text = models.TextField()
 
diff --git a/app/api/views.py b/app/api/views.py
index 015b8e17..90bb4f25 100644
--- a/app/api/views.py
+++ b/app/api/views.py
@@ -1,5 +1,3 @@
-from collections import Counter
-
 from django.conf import settings
 from django.shortcuts import get_object_or_404, redirect
 from django_filters.rest_framework import DjangoFilterBackend
@@ -15,7 +13,7 @@ from rest_framework.parsers import MultiPartParser
 from rest_framework_csv.renderers import CSVRenderer
 
 from .filters import DocumentFilter
-from .models import Project, Label, Document, Seq2seqAnnotation
+from .models import Project, Label, Document
 from .permissions import IsAdminUserAndWriteOnly, IsProjectUser, IsOwnAnnotation
 from .serializers import ProjectSerializer, LabelSerializer, DocumentSerializer, UserSerializer
 from .serializers import ProjectPolymorphicSerializer
@@ -85,20 +83,8 @@ class StatisticsAPI(APIView):
         return {'total': total, 'remaining': remaining}
 
     def label_per_data(self, project):
-        label_count = Counter()
-        user_count = Counter()
         annotation_class = project.get_annotation_class()
-        docs = project.documents.all()
-        annotations = annotation_class.objects.filter(document_id__in=docs.all())
-        if annotation_class == Seq2seqAnnotation:
-            for d in annotations.values('text', 'user__username').annotate(Count('text'), Count('user')):
-                label_count[d['text']] += d['text__count']
-                user_count[d['user__username']] += d['user__count']
-        else:
-            for d in annotations.values('label__text', 'user__username').annotate(Count('label'), Count('user')):
-                label_count[d['label__text']] += d['label__count']
-                user_count[d['user__username']] += d['user__count']
-        return label_count, user_count
+        return annotation_class.objects.get_label_per_data(project=project)
 
 
 class ApproveLabelsAPI(APIView):