diff --git a/city_metrix/layers/world_pop.py b/city_metrix/layers/world_pop.py
index d3b2aa6..a7e37d5 100644
--- a/city_metrix/layers/world_pop.py
+++ b/city_metrix/layers/world_pop.py
@@ -8,11 +8,13 @@
 class WorldPop(Layer):
     """
     Attributes:
+        year: year used for data retrieval
         spatial_resolution: raster resolution in meters (see https://github.com/stac-extensions/raster)
     """
 
-    def __init__(self, spatial_resolution=100, **kwargs):
+    def __init__(self, year=2020, spatial_resolution=100, **kwargs):
         super().__init__(**kwargs)
+        self.year = year
         self.spatial_resolution = spatial_resolution
 
     def get_data(self, bbox):
@@ -20,9 +22,9 @@ def get_data(self, bbox):
         dataset = ee.ImageCollection('WorldPop/GP/100m/pop')
         world_pop = ee.ImageCollection(dataset
                      .filterBounds(ee.Geometry.BBox(*bbox))
-                     .filter(ee.Filter.inList('year', [2020]))
+                     .filter(ee.Filter.inList('year', [self.year]))
                      .select('population')
-                     .sum()
+                     .mean()
                      )
 
         data = get_image_collection(world_pop, bbox, self.spatial_resolution, "world pop")
diff --git a/city_metrix/layers/world_pop_age_sex.py b/city_metrix/layers/world_pop_age_sex.py
index 068abd6..ec3eda1 100644
--- a/city_metrix/layers/world_pop_age_sex.py
+++ b/city_metrix/layers/world_pop_age_sex.py
@@ -23,12 +23,12 @@ def __init__(self, agesex_classes=['M_70'], year=2020, spatial_resolution=100, *
     def get_data(self, bbox):
         # load population
         dataset = ee.ImageCollection('WorldPop/GP/100m/pop_age_sex')
-        world_pop = ee.ImageCollection(dataset
-                                       .filterBounds(ee.Geometry.BBox(*bbox))
-                                       .filter(ee.Filter.inList('year', [self.year]))
-                                       .select(self.agesex_classes)
-                                       .sum()
-                                       )
+        world_pop = dataset.filterBounds(ee.Geometry.BBox(*bbox))\
+                           .filter(ee.Filter.inList('year', [self.year]))\
+                           .select(self.agesex_classes)\
+                           .mean()
+
+        world_pop = ee.ImageCollection(world_pop.reduce(ee.Reducer.sum()).rename('sum_age_sex_group'))
 
         data = get_image_collection(world_pop, bbox, self.spatial_resolution, "world pop age sex")
-        return data.population
+        return data.sum_age_sex_group