diff --git a/pgscatalog_utils/aggregate/aggregate_scores.py b/pgscatalog_utils/aggregate/aggregate_scores.py
index d57943d..71fbb43 100644
--- a/pgscatalog_utils/aggregate/aggregate_scores.py
+++ b/pgscatalog_utils/aggregate/aggregate_scores.py
@@ -16,14 +16,14 @@ def aggregate_scores():
 
     if args.split:
         logger.debug("Splitting aggregated scores by sampleset")
-        for sampleset, group in df.groupby('sampleset'):
+        for sampleset, group in df.groupby("sampleset"):
             fout = f"{sampleset}_pgs.txt.gz"
             logger.debug(f"Compressing sampleset {sampleset}, writing to {fout}")
-            group.to_csv(fout, sep='\t', compression='gzip')
+            group.to_csv(fout, sep="\t", compression="gzip")
     else:
         fout = "aggregated_scores.txt.gz"
         logger.info(f"Compressing all samplesets and writing combined scores to {fout}")
-        df.to_csv(fout, sep='\t', compression='gzip')
+        df.to_csv(fout, sep="\t", compression="gzip")
 
 
 def aggregate(scorefiles: list[str]):
@@ -33,11 +33,13 @@ def aggregate(scorefiles: list[str]):
     for i, path in enumerate(scorefiles):
         logger.debug(f"Reading {path}")
         # pandas can automatically detect zst compression, neat!
-        df = (pd.read_table(path, converters={"#IID": str}, header=0)
-              .assign(sampleset=path.split('_')[0])
-              .set_index(['sampleset', '#IID']))
+        df = (
+            pd.read_table(path, converters={"#IID": str}, header=0)
+            .assign(sampleset=path.split("_")[0])
+            .set_index(["sampleset", "#IID"])
+        )
 
-        df.index.names = ['sampleset', 'IID']
+        df.index.names = ["sampleset", "IID"]
 
         # Subset to aggregatable columns
         df = df[_select_agg_cols(df.columns)]
@@ -45,31 +47,57 @@ def aggregate(scorefiles: list[str]):
 
         # Combine DFs
         if i == 0:
-            logger.debug('Initialising combined DF')
+            logger.debug("Initialising combined DF")
             combined = df.copy()
         else:
-            logger.debug('Adding to combined DF')
+            logger.debug("Adding to combined DF")
             combined = combined.add(df, fill_value=0)
 
-    assert all([x in combined.columns for x in aggcols]), "All Aggregatable Columns are present in the final DF"
+    assert all(
+        [x in combined.columns for x in aggcols]
+    ), "All Aggregatable Columns are present in the final DF"
 
-    return combined.pipe(_calculate_average)
+    sum_df, avg_df = combined.pipe(_calculate_average)
+    # need to melt sum and avg separately to give correct value_Name to melt
+    dfs = [_melt(x, y) for x, y in zip([sum_df, avg_df], ["SUM", "AVG"])]
+    # add melted average back
+    combined = pd.concat([dfs[0], dfs[1]["AVG"]], axis=1)
+    return combined[["accession", "SUM", "DENOM", "AVG"]]
+
+
+def _melt(df, value_name):
+    df = df.melt(
+        id_vars=["DENOM"],
+        value_name=value_name,
+        var_name="accession",
+        ignore_index=False,
+    )
+    df["accession"] = df["accession"].str.replace(f"_{value_name}", "")
+    return df
 
 
 def _calculate_average(combined: pd.DataFrame):
     logger.debug("Averaging data")
-    avgs = combined.loc[:, combined.columns.str.endswith('_SUM')].divide(combined['DENOM'], axis=0)
-    avgs.columns = avgs.columns.str.replace('_SUM', '_AVG')
-    return pd.concat([combined, avgs], axis=1)
+    avgs = combined.loc[:, combined.columns.str.endswith("_SUM")].divide(
+        combined["DENOM"], axis=0
+    )
+    avgs.columns = avgs.columns.str.replace("_SUM", "_AVG")
+    avgs["DENOM"] = combined["DENOM"]
+    return combined, avgs
 
 
 def _select_agg_cols(cols):
-    keep_cols = ['DENOM']
-    return [x for x in cols if (x.endswith('_SUM') and (x != 'NAMED_ALLELE_DOSAGE_SUM')) or (x in keep_cols)]
+    keep_cols = ["DENOM"]
+    return [
+        x
+        for x in cols
+        if (x.endswith("_SUM") and (x != "NAMED_ALLELE_DOSAGE_SUM")) or (x in keep_cols)
+    ]
 
 
 def _description_text() -> str:
-    return textwrap.dedent('''
+    return textwrap.dedent(
+        """
     Aggregate plink .sscore files into a combined TSV table.
     
     This aggregation sums scores that were calculated from plink
@@ -80,20 +108,45 @@ def _description_text() -> str:
     Input .sscore files can be optionally compressed with zstd or gzip. 
     
     The aggregated output scores are compressed with gzip.
-   ''')
+   """
+    )
 
 
 def _parse_args(args=None) -> argparse.Namespace:
-    parser = argparse.ArgumentParser(description=_description_text(),
-                                     formatter_class=argparse.RawDescriptionHelpFormatter)
-    parser.add_argument('-s', '--scores', dest='scores', required=True, nargs='+',
-                        help='<Required> List of scorefile paths. Use a wildcard (*) to select multiple files.')
-    parser.add_argument('-o', '--outdir', dest='outdir', required=True,
-                        default='scores/', help='<Required> Output directory to store downloaded files')
-    parser.add_argument('--split', dest='split', required=False, action=argparse.BooleanOptionalAction,
-                        help='<Optional> Make one aggregated file per sampleset')
-    parser.add_argument('-v', '--verbose', dest='verbose', action='store_true',
-                        help='<Optional> Extra logging information')
+    parser = argparse.ArgumentParser(
+        description=_description_text(),
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+    )
+    parser.add_argument(
+        "-s",
+        "--scores",
+        dest="scores",
+        required=True,
+        nargs="+",
+        help="<Required> List of scorefile paths. Use a wildcard (*) to select multiple files.",
+    )
+    parser.add_argument(
+        "-o",
+        "--outdir",
+        dest="outdir",
+        required=True,
+        default="scores/",
+        help="<Required> Output directory to store downloaded files",
+    )
+    parser.add_argument(
+        "--split",
+        dest="split",
+        required=False,
+        action=argparse.BooleanOptionalAction,
+        help="<Optional> Make one aggregated file per sampleset",
+    )
+    parser.add_argument(
+        "-v",
+        "--verbose",
+        dest="verbose",
+        action="store_true",
+        help="<Optional> Extra logging information",
+    )
     return parser.parse_args(args)